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Ion trap long-range XY model for quantum state transfer and optimal spatial search Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-06-12 Dylan Lewis, Leonardo Banchi, Yi Hong Teoh, Rajibul Islam, Sougato Bose
Linear ion trap chains are a promising platform for quantum computation and simulation. The XY model with long-range interactions can be implemented with a single side-band Mølmer–Sørensen scheme, giving interactions that decay as 1/rα , where α parameterises the interaction range. Lower α leads to longer range interactions, allowing faster long-range gate operations for quantum computing. However
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Speeding up qubit control with bipolar single-flux-quantum pulse sequences Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-06-09 Vsevolod Vozhakov, Marina Bastrakova, Nikolay Klenov, Arkady Satanin, Igor Soloviev
The development of quantum computers based on superconductors requires the improvement of the qubit state control approach aimed at the increase of the hardware energy efficiency. A promising solution to this problem is the use of superconducting digital circuits operating with single-flux-quantum (SFQ) pulses, moving the qubit control system into the cold chamber. However, the qubit gate time under
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Predicting the minimum control time of quantum protocols with artificial neural networks Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-06-01 Sofia Sevitz, Nicolás Mirkin, Diego A Wisniacki
Quantum control relies on the driving of quantum states without the loss of coherence, thus the leakage of quantum properties into the environment over time is a fundamental challenge. One work-around is to implement fast protocols, hence the Minimal Control Time (MCT) is of upmost importance. Here, we employ a machine learning network in order to estimate the MCT in a state transfer protocol. An unsupervised
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Stationary quantum entanglement and steering between two distant macromagnets Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-30 Jikun Xie, Huaiyang Yuan, Shengli Ma, Shaoyan Gao, Fuli Li, Rembert A Duine
Generating and manipulating magnon quantum states for quantum information processing is a central topic in quantum magnonics. The conventional strategy amplifies the nonlinear interaction among magnons to manifest their quantum correlations at cryogenic temperatures, which is challenging for magnets with vanishingly small nonlinearities. Here we propose an unconventional approach to prepare entangled
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Do quantum circuit Born machines generalize? Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-30 Kaitlin Gili, Mohamed Hibat-Allah, Marta Mauri, Chris Ballance, Alejandro Perdomo-Ortiz
In recent proposals of quantum circuit models for generative tasks, the discussion about their performance has been limited to their ability to reproduce a known target distribution. For example, expressive model families such as quantum circuit Born machines (QCBMs) have been almost entirely evaluated on their capability to learn a given target distribution with high accuracy. While this aspect may
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Dissipative stabilization of entangled qubit pairs in quantum arrays with a single localized dissipative channel Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-26 Jacopo Angeletti, Stefano Zippilli, David Vitali
We study the dissipative stabilization of entangled states in arrays of quantum systems. Specifically, we are interested in the states of qubits (spin- 1/2 ) which may or may not interact with one or more cavities (bosonic modes). In all cases only one element, either a cavity or a qubit, is lossy and irreversibly coupled to a reservoir. When the lossy element is a cavity, we consider a squeezed reservoir
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Reducing molecular electronic Hamiltonian simulation cost for linear combination of unitaries approaches Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-26 Ignacio Loaiza, Alireza Marefat Khah, Nathan Wiebe, Artur F Izmaylov
We consider different linear combination of unitaries (LCU) decompositions for molecular electronic structure Hamiltonians. Using these LCU decompositions for Hamiltonian simulation on a quantum computer, the main figure of merit is the 1-norm of their coefficients, which is associated with the quantum circuit complexity. It is derived that the lowest possible LCU 1-norm for a given Hamiltonian is
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Many-body spin rotation by adiabatic passage in spin-1/2 XXZ chains of ultracold atoms Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-25 Ivana Dimitrova, Stuart Flannigan, Yoo Kyung Lee, Hanzhen Lin, Jesse Amato-Grill, Niklas Jepsen, Ieva Čepaitė, Andrew J Daley, Wolfgang Ketterle
Quantum many-body phases offer unique properties and emergent phenomena, making them an active area of research. A promising approach for their experimental realization in model systems is to adiabatically follow the ground state of a quantum Hamiltonian from a product state of isolated particles to one that is strongly-correlated. Such protocols are relevant also more broadly in coherent quantum annealing
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Real-time frequency estimation of a qubit without single-shot-readout Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-22 I Zohar, B Haylock, Y Romach, M J Arshad, N Halay, N Drucker, R Stöhr, A Denisenko, Y Cohen, C Bonato, A Finkler
Quantum sensors can potentially achieve the Heisenberg limit of sensitivity over a large dynamic range using quantum algorithms. The adaptive phase estimation algorithm (PEA) is one example that was proven to achieve such high sensitivities with single-shot readout (SSR) sensors. However, using the adaptive PEA on a non-SSR sensor is not trivial due to the low contrast nature of the measurement. The
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Entanglement-assisted multi-aperture pulse-compression radar for angle resolving detection Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-16 Bo-Han Wu, Saikat Guha, Quntao Zhuang
Entanglement has been known to boost target detection, despite it being destroyed by lossy-noisy propagation. Recently, Zhuang and Shapiro (2022 Phys. Rev. Lett. 128 010501) proposed a quantum pulse-compression radar to extend entanglement’s benefit to target range estimation. In a radar application, many other aspects of the target are of interest, including angle, velocity and cross section. In this
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Paving the way toward 800 Gbps quantum-secured optical channel deployment in mission-critical environments Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-15 Marco Pistoia, Omar Amer, Monik R Behera, Joseph A Dolphin, James F Dynes, Benny John, Paul A Haigh, Yasushi Kawakura, David H Kramer, Jeffrey Lyon, Navid Moazzami, Tulasi D Movva, Antigoni Polychroniadou, Suresh Shetty, Greg Sysak, Farzam Toudeh-Fallah, Sudhir Upadhyay, Robert I Woodward, Andrew J Shields
This article describes experimental research studies conducted toward understanding the implementation aspects of high-capacity quantum-secured optical channels in mission-critical metro-scale operational environments using quantum key distribution (QKD) technology. To the best of our knowledge, this is the first time that an 800 Gbps quantum-secured optical channel—along with several other dense wavelength
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Sequence of penalties method to study excited states using VQE Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-15 R Carobene, S Barison, A Giachero
We propose an extension of the variational quantum eigensolver (VQE) that leads to more accurate energy estimations and can be used to study excited states. The method is based on the introduction of a sequence of increasing penalties in the cost function. This approach does not require circuit modifications and thus can be applied with no additional depth cost. Through numerical simulations, we show
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Logical qubit implementation for quantum annealing: augmented Lagrangian approach Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-10 Hristo N Djidjev
Solving optimization problems on quantum annealers (QA) usually requires each variable of the problem to be represented by a connected set of qubits called a logical qubit or a chain. Chain weights, in the form of ferromagnetic coupling between the chain qubits, are applied so that the physical qubits in a chain favor taking the same value in low energy samples. Assigning a good chain-strength value
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Accelerating the variational quantum eigensolver using parallelism Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-09 Lana Mineh, Ashley Montanaro
Quantum computers are getting larger and larger, but device fidelities may not be able to keep up with the increase in qubit numbers. One way to make use of a large device that has a limited gate depth is to run many small circuits simultaneously. In this paper we detail our investigations into running circuits in parallel on the Rigetti Aspen-M-1 device. We run two-qubit circuits in parallel to solve
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The implementation of Shannon-limited polar codes-based information reconciliation for quantum key distribution Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-09 Junbin Guo, Bangying Tang, Tingqin Lai, Xiaolin Liang, Siyuan Zhang, Zhiyu Tian, Jinquan Huang, Xuelin Yuan, Wanrong Yu, Bo Liu, Shaobo Luo, Shihai Sun
Quantum key distribution (QKD) gives a way to generate unconditionally secure keys for two remote users, Alice and Bob. Information reconciliation (IR), which can correct the errors caused by the imperfections of the QKD systems, is a critical component in QKD. Due to the high-security requirements and large volumes of data processing, robustness and efficiency are two main factors that must be considered
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Quantum Stirling engine based on dinuclear metal complexes Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-05 Clebson Cruz, Hamid-Reza Rastegar-Sedehi, Maron F Anka, Thiago R de Oliveira, Mario Reis
Low-dimensional metal complexes are versatile materials with tunable physical and chemical properties that make these systems promising platforms for caloric applications. In this context, this work proposes a quantum Stirling cycle based on a dinuclear metal complex as a working substance. The results show that the quantum cycle operational modes can be managed when considering the change in the magnetic
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Emergent complex quantum networks in continuous-variables non-Gaussian states Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-04 Mattia Walschaers, Bhuvanesh Sundar, Nicolas Treps, Lincoln D Carr, Valentina Parigi
We use complex network theory to study a class of photonic continuous variable quantum states that present both multipartite entanglement and non-Gaussian statistics. We consider the intermediate scale of several dozens of modes at which such systems are already hard to characterize. In particular, the states are built from an initial imprinted cluster state created via Gaussian entangling operations
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Multilayered logical qubits and synthesized quantum bits Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-03 Ki-Sung Jin, Gyu-Il Cha
Quantum error correction is likely to be key in obtaining near term quantum advantage. We propose a novel method for providing multiple logical qubits in the correction of quantum errors using classical computers. The core idea of our work is built upon two main pillars: dividing the Hilbert space into reduced Hilbert spaces with individual logical qubits and synthesizing the reduced Hilbert spaces
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Charging a quantum battery in a non-Markovian environment: a collisional model approach Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-05-02 Daniele Morrone, Matteo A C Rossi, Andrea Smirne, Marco G Genoni
We study the effect of non-Markovianity in the charging process of an open-system quantum battery. We employ a collisional model framework, where the environment is described by a discrete set of ancillary systems and memory effects in the dynamics can be introduced by allowing these ancillas to interact. We study in detail the behaviour of the steady-state ergotropy and the impact of the information
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Quantum scrambling via accessible tripartite information Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-04-28 Gabriele Lo Monaco, Luca Innocenti, Dario Cilluffo, Dario A Chisholm, Salvatore Lorenzo, G Massimo Palma
Quantum information scrambling (QIS), from the perspective of quantum information theory, is generally understood as local non-retrievability of information evolved through some dynamical process, and is often quantified via entropic quantities such as the tripartite information. We argue that this approach comes with a number of issues, in large part due to its reliance on quantum mutual informations
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Controlled expansion of shell-shaped Bose–Einstein condensates Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-04-27 Patrick Boegel, Alexander Wolf, Matthias Meister, Maxim A Efremov
Motivated by the recent experimental realization of ultracold quantum gases in shell topology, we propose a straightforward implementation of matter-wave lensing techniques for shell-shaped Bose–Einstein condensates. This approach allows to significantly extend the free evolution time of the condensate shell after release from the trap and enables the study of novel quantum many-body effects on curved
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Noise dynamics of quantum annealers: estimating the effective noise using idle qubits Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-04-21 Elijah Pelofske, Georg Hahn, Hristo N Djidjev
Quantum annealing is a type of analog computation that aims to use quantum mechanical fluctuations in search of optimal solutions of QUBO (quadratic unconstrained binary optimization) or, equivalently, Ising problems. Since NP-hard problems can in general be mapped to Ising and QUBO formulations, the quantum annealing paradigm has the potential to help solve various NP-hard problems. Current quantum
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Is everything quantum ‘spooky and weird’? An exploration of popular communication about quantum science and technology in TEDx talks Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-04-21 Aletta Lucia Meinsma, Sanne Willemijn Kristensen, W Gudrun Reijnierse, Ionica Smeets, Julia Cramer
Previous studies have identified four potential issues related to the popularisation of quantum science and technology. These include framing quantum science and technology as spooky and enigmatic, a lack of explaining underlying quantum concepts of quantum 2.0 technology, framing quantum technology narrowly in terms of public good and having a strong focus on quantum computing. Before assessing the
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Generation of a time–bin Greenberger–Horne–Zeilinger state with an optical switch Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-04-11 Hsin-Pin Lo, Takuya Ikuta, Koji Azuma, Toshimori Honjo, William J Munro, Hiroki Takesue
Multipartite entanglement is a critical resource in quantum information processing that exhibits much richer phenomenon and stronger correlations than in bipartite systems. This advantage is also reflected in its multi-user applications. Although many demonstrations have used photonic polarization qubits, polarization-mode dispersion confines the transmission of photonic polarization qubits through
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Towards a scalable discrete quantum generative adversarial neural network Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-04-04 Smit Chaudhary, Patrick Huembeli, Ian MacCormack, Taylor L Patti, Jean Kossaifi, Alexey Galda
Quantum generative adversarial networks (QGANs) have been studied in the context of quantum machine learning for several years, but there has not been yet a proposal for a fully QGAN with both, a quantum generator and discriminator. We introduce a fully QGAN intended for use with binary data. The architecture incorporates several features found in other classical and quantum machine learning models
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Quantum mixed state compiling Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-04-04 Nic Ezzell, Elliott M Ball, Aliza U Siddiqui, Mark M Wilde, Andrew T Sornborger, Patrick J Coles, Zoë Holmes
The task of learning a quantum circuit to prepare a given mixed state is a fundamental quantum subroutine. We present a variational quantum algorithm (VQA) to learn mixed states which is suitable for near-term hardware. Our algorithm represents a generalization of previous VQAs that aimed at learning preparation circuits for pure states. We consider two different ansätze for compiling the target state;
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Propagating quantum microwaves: towards applications in communication and sensing Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-03-28 Mateo Casariego, Emmanuel Zambrini Cruzeiro, Stefano Gherardini, Tasio Gonzalez-Raya, Rui André, Gonçalo Frazão, Giacomo Catto, Mikko Möttönen, Debopam Datta, Klaara Viisanen, Joonas Govenius, Mika Prunnila, Kimmo Tuominen, Maximilian Reichert, Michael Renger, Kirill G Fedorov, Frank Deppe, Harriet van der Vliet, A J Matthews, Yolanda Fernández, R Assouly, R Dassonneville, B Huard, Mikel Sanz, Yasser
The field of propagating quantum microwaves is a relatively new area of research that is receiving increased attention due to its promising technological applications, both in communication and sensing. While formally similar to quantum optics, some key elements required by the aim of having a controllable quantum microwave interface are still on an early stage of development. Here, we argue where
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Supervised learning of random quantum circuits via scalable neural networks Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-03-27 Simone Cantori, David Vitali, Sebastiano Pilati
Predicting the output of quantum circuits is a hard computational task that plays a pivotal role in the development of universal quantum computers. Here we investigate the supervised learning of output expectation values of random quantum circuits. Deep convolutional neural networks (CNNs) are trained to predict single-qubit and two-qubit expectation values using databases of classically simulated
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Probing the dynamics and coherence of a semiconductor hole spin via acoustic phonon-assisted excitation Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-03-20 N Coste, M Gundin, D A Fioretto, S E Thomas, C Millet, E Mehdi, N Somaschi, M Morassi, M Pont, A Lemaître, N Belabas, O Krebs, L Lanco, P Senellart
Spins in semiconductor quantum dots (QDs) are promising local quantum memories to generate polarization-encoded photonic cluster states, as proposed in the pioneering Lindner and Rudolph scheme (2009 Phys. Rev. Lett. 103 113602). However, harnessing the polarization degree of freedom of the optical transitions is hindered by resonant excitation schemes that are widely used to obtain high photon indistinguishability
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Lossy SU(1,1) interferometers in the single-photon-pair regime Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-03-17 Matteo Santandrea, Kai-Hong Luo, Michael Stefszky, Jan Sperling, Harald Herrmann, Benjamin Brecht, Christine Silberhorn
The success of quantum technologies is intimately connected to the possibility of using them in real-world applications. This requires the system to be comprehensively modeled including various relevant experimental parameters. To this aim, in this paper, we study the performance of lossy SU(1,1) interferometers in the single-photon pair regime, posing particular attention to the different amount of
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Signatures of a sampling quantum advantage in driven quantum many-body systems Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-03-13 Jirawat Tangpanitanon, Supanut Thanasilp, Marc-Antoine Lemonde, Ninnat Dangniam, Dimitris G Angelakis
A crucial milestone in the field of quantum simulation and computation is to demonstrate that a quantum device can perform a computation task that is classically intractable. A key question is to identify setups that can achieve such goal within current technologies. In this work, we provide formal evidence that sampling bit-strings from a periodic evolution of a unitary drawn from the circular orthogonal
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Accessing the topological Mott insulator in cold atom quantum simulators with realistic Rydberg dressing Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-03-07 Lorenzo Cardarelli, Sergi Julià-Farré, Maciej Lewenstein, Alexandre Dauphin, Markus Müller
The interplay between many-body interactions and the kinetic energy gives rise to rich phase diagrams hosting, among others, interaction-induced topological phases. These phases are characterized by both a local order parameter and a global topological invariant, and can exhibit exotic ground states such as self-trapped polarons and interaction-induced edge states. In this work, we investigate a realistic
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Quantum control of tunable-coupling transmons using dynamical invariants of motion Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-03-07 H Espinós, I Panadero, J J García-Ripoll, E Torrontegui
We analyze the implementation of a fast nonadiabatic CZ gate between two transmon qubits with tunable coupling. The gate control method is based on a theory of dynamical invariants which leads to reduced leakage and robustness against decoherence. The gate is based on a description of the resonance between the |11⟩ and |20⟩ using an effective Hamiltonian with the six lowest energy states. A modification
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From counterportation to local wormholes Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-03-02 Hatim Salih
We propose an experimental realisation of the protocol for the counterfactual disembodied transport of an unknown qubit—or what we call counterportation—where sender and receiver, remarkably, exchange no particles. We employ cavity quantum electrodynamics, estimating resources for beating the classical fidelity limit—except, unlike teleportation, no pre-shared entanglement nor classical communication
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Hybrid quantum–classical convolutional neural networks with privacy quantum computing Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-27 Siwei Huang, Yan Chang, Yusheng Lin, Shibin Zhang
Machine learning algorithms help us discover knowledge from big data. Data used for training or prediction often contain private information about users. Discovering knowledge while protecting data or user privacy is the way machine learning is expected, especially in the cloud environment. Quantum machine learning is a kind of machine learning that realizes parallel acceleration by quantum superposition
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A fully passive transmitter for decoy-state quantum key distribution Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-27 Víctor Zapatero, Wenyuan Wang, Marcos Curty
A passive quantum key distribution (QKD) transmitter generates the quantum states prescribed by a QKD protocol at random, combining a fixed quantum mechanism and a post-selection step. By circumventing the use of active optical modulators externally driven by random number generators, passive QKD transmitters offer immunity to modulator side channels and potentially enable higher frequencies of operation
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Effects of quantum resources and noise on the statistical complexity of quantum circuits Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-17 Kaifeng Bu, Dax Enshan Koh, Lu Li, Qingxian Luo, Yaobo Zhang
We investigate how the addition of quantum resources changes the statistical complexity of quantum circuits by utilizing the framework of quantum resource theories. Measures of statistical complexity that we consider include the Rademacher complexity and the Gaussian complexity, which are well-known measures in computational learning theory that quantify the richness of classes of real-valued functions
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A strain-engineered graphene qubit in a nanobubble Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-17 Hee Chul Park, JungYun Han, Nojoon Myoung
We propose a controllable qubit in a graphene nanobubble (NB) with emergent two-level systems (TLSs) induced by pseudo-magnetic fields (PMFs). We found that double quantum dots can be created by the strain-induced PMFs of a NB, and also that their quantum states can be manipulated by either local gate potentials or the PMFs. Graphene qubits clearly exhibit avoided crossing behavior as electrical detuning
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Quantum memories for fundamental science in space Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-09 Jan-Michael Mol, Luisa Esguerra, Matthias Meister, David Edward Bruschi, Andreas Wolfgang Schell, Janik Wolters, Lisa Wörner
Investigating and verifying the connections between the foundations of quantum mechanics and general relativity will require extremely sensitive quantum experiments. To provide ultimate insight into this fascinating area of physics, the realization of dedicated experiments in space will sooner or later become a necessity. Quantum technologies, and among them quantum memories in particular, are providing
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High-resolution spectroscopy of a single nitrogen-vacancy defect at zero magnetic field Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-09 Shashank Kumar, Pralekh Dubey, Sudhan Bhadade, Jemish Naliyapara, Jayita Saha, Phani Peddibhotla
We report a study of high-resolution microwave spectroscopy of nitrogen-vacancy (NV) centers in diamond crystals at and around zero magnetic field. We observe characteristic splitting and transition imbalance of the hyperfine transitions, which originate from level anti-crossings (LACs) in the presence of a transverse effective field. We use pulsed electron spin resonance spectroscopy to measure the
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Simulating Majorana zero modes on a noisy quantum processor Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-09 Kevin J Sung, Marko J Rančić, Olivia T Lanes, Nicholas T Bronn
The simulation of systems of interacting fermions is one of the most anticipated applications of quantum computers. The most interesting simulations will require a fault-tolerant quantum computer, and building such a device remains a long-term goal. However, the capabilities of existing noisy quantum processors have steadily improved, sparking an interest in running simulations that, while not necessarily
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Hybrid and heterogeneous photonic integrated near-infrared InGaAs/InAlAs single-photon avalanche diode Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-08 Jishen Zhang, Haiwen Xu, Gong Zhang, Yue Chen, Haibo Wang, Kian Hua Tan, Satrio Wicaksono, Chen Sun, Qiwen Kong, Chao Wang, Charles Ci Wen Lim, Soon-Fatt Yoon, Xiao Gong
We have demonstrated the integrated indium gallium arsenide/indium aluminum arsenide (InGaAs/InAlAs) single-photon avalanche diodes (SPAD) with silicon (Si) waveguides and grating couplers on the Silicon-on-insulator substrate. A vertical coupling scheme is adopted which allows the use of a thick bonding interlayer for high yield. The epoxy ‘SU-8’ is selected to be the adhesion layer with a low transmission
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Democratization of quantum technologies Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-07 Zeki C Seskir, Steven Umbrello, Christopher Coenen, Pieter E Vermaas
As quantum technologies (QT) advance, their potential impact on and relation with society has been developing into an important issue for exploration. In this paper, we investigate the topic of democratization in the context of QT, particularly quantum computing. The paper contains three main sections. First, we briefly introduce different theories of democracy (participatory, representative, and deliberative)
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Exploring the limits of ultracold atoms in space Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-06 R J Thompson, D C Aveline, Sheng-Wey Chiow, E R Elliott, J R Kellogg, J M Kohel, M S Sbroscia, C Schneider, J R Williams, N Lundblad, C A Sackett, D Stamper-Kurn, L Woerner
Existing space-based cold atom experiments have demonstrated the utility of microgravity for improvements in observation times and for minimizing the expansion energy and rate of a freely evolving coherent matter wave. In this paper we explore the potential for space-based experiments to extend the limits of ultracold atoms utilizing not just microgravity, but also other aspects of the space environment
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Perspective on quantum bubbles in microgravity Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-06 Nathan Lundblad, David C Aveline, Antun Balaž, Elliot Bentine, Nicholas P Bigelow, Patrick Boegel, Maxim A Efremov, Naceur Gaaloul, Matthias Meister, Maxim Olshanii, Carlos A R Sá de Melo, Andrea Tononi, Smitha Vishveshwara, Angela C White, Alexander Wolf, Barry M Garraway
Progress in understanding quantum systems has been driven by the exploration of the geometry, topology, and dimensionality of ultracold atomic systems. The NASA Cold Atom Laboratory (CAL) aboard the International Space Station has enabled the study of ultracold atomic bubbles, a terrestrially-inaccessible topology. Proof-of-principle bubble experiments have been performed on CAL with an radiofrequency-dressing
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Coherent rotation of a single spin via adiabatic half passage in the presence of a ferromagnetic vortex Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-02 R Badea, M S Wolf, J Berezovsky
We experimentally and numerically study possible implementations for π/2 rotations of a single nitrogen-vacancy defect spin state in proximity to a magnetic vortex core. Dynamically controlled magnetic vortex cores have been suggested as a means to provide nanoscale, rapidly-tunable magnetic fields for spin qubit addressability and control. However, driven and thermal non-equilibrium dynamics of the
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A multiplexed synthesizer for non-Gaussian photonic quantum state generation Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-02-02 M F Melalkia, J Huynh, S Tanzilli, V D’Auria, J Etesse
Disposing of simple and efficient sources for photonic states with non-classical photon statistics is of paramount importance for implementing quantum computation and communication protocols. In this work, we propose an innovative approach that drastically simplifies the preparation of non-Gaussian states as compared to previous proposals, by taking advantage from the multiplexing capabilities offered
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Efficient motional-mode characterization for high-fidelity trapped-ion quantum computing Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-01-31 Mingyu Kang, Qiyao Liang, Ming Li, Yunseong Nam
To achieve high-fidelity operations on a large-scale quantum computer, the parameters of the physical system must be efficiently characterized with high accuracy. For trapped ions, the entanglement between qubits are mediated by the motional modes of the ion chain, and thus characterizing the motional-mode parameters becomes essential. In this paper, we develop and explore physical models that accurately
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Proposal for an active whispering-gallery microclock Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-01-30 Deshui Yu, Frank Vollmer, Shougang Zhang
Optical atomic clocks with compact size, reduced weight and low power consumption have broad out-of-the-lab applications such as satellite-based geo-positioning and communication engineering. Here, we propose an active optical microclock based on the lattice-trapped atoms evanescently interacting with a whispering-gallery-mode microcavity. Unlike the conventional passive clock scheme, the active operation
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Variational Hamiltonian simulation for translational invariant systems via classical pre-processing Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-01-30 Refik Mansuroglu, Timo Eckstein, Ludwig Nützel, Samuel A Wilkinson, Michael J Hartmann
The simulation of time evolution of large quantum systems is a classically challenging and in general intractable task, making it a promising application for quantum computation. A Trotter–Suzuki approximation yields an implementation thereof, where a higher approximation accuracy can be traded for an increased gate count. In this work, we introduce a variational algorithm which uses solutions of classical
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Optimal quantum control via genetic algorithms for quantum state engineering in driven-resonator mediated networks Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-01-25 Jonathon Brown, Mauro Paternostro, Alessandro Ferraro
We employ a machine learning-enabled approach to quantum state engineering based on evolutionary algorithms. In particular, we focus on superconducting platforms and consider a network of qubits—encoded in the states of artificial atoms with no direct coupling—interacting via a common single-mode driven microwave resonator. The qubit-resonator couplings are assumed to be in the resonant regime and
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Efficient matter-wave lensing of ultracold atomic mixtures Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-01-25 Matthias Meister, Albert Roura
Mixtures of ultracold quantum gases are at the heart of high-precision quantum tests of the weak equivalence principle, where extremely low expansion rates have to be reached with matter-wave lensing techniques. We propose to simplify this challenging atom-source preparation by employing magic laser wavelengths for the optical lensing potentials, which guarantee that all atomic species follow identical
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Automatic generation of Grover quantum oracles for arbitrary data structures Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-01-23 Raphael Seidel, Colin Kai-Uwe Becker, Sebastian Bock, Nikolay Tcholtchev, Ilie-Daniel Gheorghe-Pop, Manfred Hauswirth
The steadily growing research interest in quantum computing—together with the accompanying technological advances in the realization of quantum hardware—fuels the development of meaningful real-world applications, as well as implementations for well-known quantum algorithms. One of the most prominent examples till today is Grover’s algorithm, which can be used for efficient search in unstructured databases
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Is quantum computing green? An estimate for an energy-efficiency quantum advantage Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-01-19 Daniel Jaschke, Simone Montangero
The quantum advantage threshold determines when a quantum processing unit (QPU) is more efficient with respect to classical computing hardware in terms of algorithmic complexity. The ‘green’ quantum advantage threshold—based on a comparison of energetic efficiency between the two—is going to play a fundamental role in the comparison between quantum and classical hardware. Indeed, its characterization
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Daylight entanglement-based quantum key distribution with a quantum dot source Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-01-18 F Basso Basset, M Valeri, J Neuwirth, E Polino, M B Rota, D Poderini, C Pardo, G Rodari, E Roccia, S F Covre da Silva, G Ronco, N Spagnolo, A Rastelli, G Carvacho, F Sciarrino, R Trotta
Entanglement-based quantum key distribution can enable secure communication in trusted node-free networks and over long distances. Although implementations exist both in fiber and in free space, the latter approach is often considered challenging due to environmental factors. Here, we implement a quantum communication protocol during daytime for the first time using a quantum dot source. This technology
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Research campaign: Macroscopic quantum resonators (MAQRO) Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-01-05 Rainer Kaltenbaek, Markus Arndt, Markus Aspelmeyer, Peter F Barker, Angelo Bassi, James Bateman, Alessio Belenchia, Joel Bergé, Claus Braxmaier, Sougato Bose, Bruno Christophe, Garrett D Cole, Catalina Curceanu, Animesh Datta, Maxime Debiossac, Uroš Delić, Lajos Diósi, Andrew A Geraci, Stefan Gerlich, Christine Guerlin, Gerald Hechenblaikner, Antoine Heidmann, Sven Herrmann, Klaus Hornberger, Ulrich
The objective of the proposed macroscopic quantum resonators (MAQRO) mission is to harness space for achieving long free-fall times, extreme vacuum, nano-gravity, and cryogenic temperatures to test the foundations of physics in macroscopic quantum experiments at the interface with gravity. Developing the necessary technologies, achieving the required sensitivities and providing the necessary isolation
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On the impact of realistic point sources in spatial mode demultiplexing super resolution imaging Quantum Sci. Technol. (IF 6.7) Pub Date : 2023-01-04 Alexander B Greenwood, Ruth Oulton, Henkjan Gersen
The desire to push beyond ‘Rayleigh’s curse’ has resulted in new techniques for super resolution imaging by deconstructing scattered light from point sources into several spatial modes, as coupling to higher order modes is exquisitely sensitive to lateral displacement. Here we implement such an approach for high numerical aperture objectives and demonstrate that for gold nanoparticles, their intrinsic
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Hybrid normal-superconducting Aharonov-Bohm quantum thermal device Quantum Sci. Technol. (IF 6.7) Pub Date : 2022-12-30 Gianmichele Blasi, Francesco Giazotto, Géraldine Haack
We propose and theoretically investigate the behavior of a ballistic Aharonov-Bohm (AB) ring when embedded in a N-S two-terminal setup, consisting of a normal metal (N) and superconducting (S) leads. This device is based on available current technologies and we show in this work that it constitutes a promising hybrid quantum thermal device, as a quantum heat engine and quantum thermal rectifier. Remarkably
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Entangling mechanical vibrations of two massive ferrimagnets by fully exploiting the nonlinearity of magnetostriction Quantum Sci. Technol. (IF 6.7) Pub Date : 2022-12-23 Hang Qian, Zhi-Yuan Fan, Jie Li
Quantum entanglement in the motion of macroscopic objects is of significance to both fundamental studies and quantum technologies. Here we show how to entangle the mechanical vibration modes of two massive ferrimagnets that are placed in the same microwave cavity. Each ferrimagnet supports a magnon mode and a low-frequency vibration mode coupled by the magnetostrictive force. The two magnon modes are
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Qade: solving differential equations on quantum annealers Quantum Sci. Technol. (IF 6.7) Pub Date : 2022-12-21 Juan Carlos Criado, Michael Spannowsky
We present a general method, called Qade, for solving differential equations using a quantum annealer. One of the main advantages of this method is its flexibility and reliability. On current devices, Qade can solve systems of coupled partial differential equations that depend linearly on the solution and its derivatives, with non-linear variable coefficients and arbitrary inhomogeneous terms. We test