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Quantum integration of decay rates at second order in perturbation theory Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-12 Jorge J Martínez de Lejarza, David F Rentería-Estrada, Michele Grossi, Germán Rodrigo
We present the first quantum computation of a total decay rate in high-energy physics at second order in perturbative quantum field theory. This work underscores the confluence of two recent cutting-edge advances. On the one hand, the quantum integration algorithm quantum Fourier iterative amplitude estimation, which efficiently decomposes the target function into its Fourier series through a quantum
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Continuous-variable quantum key distribution with noisy squeezed states Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-11 Akash nag Oruganti, Ivan Derkach, Radim Filip, Vladyslav C Usenko
We address the crucial role of noisy squeezing in security and performance of continuous-variable (CV) quantum key distribution (QKD) protocols. Squeezing has long been recognized for its numerous advantages in CV QKD, such as enhanced robustness against channel noise and loss, and improved secret key rates. However, the excess noise of the squeezed states, that unavoidably originates already from
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Comparing three generations of D-Wave quantum annealers for minor embedded combinatorial optimization problems Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-11 Elijah Pelofske
Quantum annealing (QA) is a novel type of analog computation that aims to use quantum mechanical fluctuations to search for optimal solutions of Ising problems. QA in the transverse Ising model, implemented on D-Wave quantum processing units, are available as cloud computing resources. In this study we report concise benchmarks across three generations of D-Wave quantum annealers, consisting of four
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Self-guided tomography of time-frequency qudits Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-11 Laura Serino, Markus Rambach, Benjamin Brecht, Jacquiline Romero, Christine Silberhorn
High-dimensional time-frequency encodings have the potential to significantly advance quantum information science; however, practical applications require precise knowledge of the encoded quantum states, which becomes increasingly challenging for larger Hilbert spaces. Self-guided tomography (SGT) has emerged as a practical and scalable technique for this purpose in the spatial domain. Here, we apply
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Quantum-enhanced clock synchronization using prior statistical information Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-10 Ronakraj K Gosalia, Robert Malaney
Optical frequency combs (OFCs) are paving the way for an unprecedented level of precision in synchronizing optical clocks over free-space. However, the conventional intensity-based strategy for estimating the timing offset between two OFCs is sub-optimal, whereas a strategy based on temporal modes can achieve the optimal precision bound under ideal conditions. In practice, the performance of both strategies
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Proof-of-work consensus by quantum sampling Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-07 Deepesh Singh, Gopikrishnan Muraleedharan, Boxiang Fu, Chen-Mou Cheng, Nicolas Roussy Newton, Peter P Rohde, Gavin K Brennen
Since its advent in 2011, boson sampling has been a preferred candidate for demonstrating quantum advantage because of its simplicity and near-term requirements compared to other quantum algorithms. We propose to use a variant, called coarse-grained boson-sampling (CGBS), as a quantum proof-of-work (PoW) scheme for blockchain consensus. The miners perform boson sampling using input states that depend
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Adaptive circuit learning of born machine: towards realization of amplitude embedding and quantum data loading Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-07 Chun-Tse Li, Hao-Chung Cheng
Quantum data loading plays a central role in quantum algorithms and quantum information processing. Many quantum algorithms hinge on the ability to prepare arbitrary superposition states as a subroutine, with claims of exponential speedups often predicated on access to an efficient data-loading oracle. In practice, constructing a circuit to prepare a generic n-qubit quantum state typically demands
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Quantum thermal machine as a rectifier Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-07 M Santiago-García, O Pusuluk, Ö E Müstecaplıoğlu, B Çakmak, R Román-Ancheyta
We study a chain of interacting individual quantum systems connected to heat baths at different temperatures on both ends. Starting with the two-system case, we thoroughly investigate the conditions for heat rectification (asymmetric heat transport), compute thermal conductance, and generalize the results to longer chains. We find that heat rectification in the weak coupling regime can be independent
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Accelerating multipartite entanglement generation in non-Hermitian superconducting qubits Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-07 Chimdessa Gashu Feyisa, J-S You, Huan-Yu Ku, H H Jen
Open quantum systems are susceptible to losses in information, energy, and particles due to their surrounding environment. One novel strategy to mitigate these losses is to transform them into advantages for quantum technologies through tailored non-Hermitian quantum systems. In this work, we theoretically propose a fast generation of multipartite entanglement in non-Hermitian qubits. Our findings
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Experimental simulation of daemonic work extraction in open quantum batteries on a digital quantum computer Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-06 Seyed Navid Elyasi, Matteo A C Rossi, Marco G Genoni
The possibility of extracting more work from a physical system thanks to the information obtained from measurements has been a topic of fundamental interest in the context of thermodynamics since the formulation of the Maxwell’s demon thought experiment. We here consider this problem from the perspective of an open quantum battery interacting with an environment that can be continuously measured. By
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Quadrature-PT symmetry: classical-to-quantum transition in noise fluctuations Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-06 Wencong Wang, Yanhua Zhai, Dongmei Liu, Xiaoshun Jiang, Saeid Vashahri Ghamsari, Jianming Wen
While gain-loss-coupled photonic platforms have achieved significant success in studying classical parity-time (PT) symmetry, they encounter challenges in demonstrating pure quantum effects due to incompatible operator transformations and Langevin noise. Here, we present compelling evidence that a non-Hermitian (NH) twin-beam system, undergoing phase-sensitive amplification and balanced loss, not only
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Asymmetric secure multi-party quantum computation with weak clients against dishonest majority Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-06 Theodoros Kapourniotis, Elham Kashefi, Dominik Leichtle, Luka Music, Harold Ollivier
Secure multi-party computation (SMPC) protocols allow several parties distrusting each other to collectively compute a function on their inputs, without revealing the input values. In this paper, we introduce a protocol that lifts SMPC to its quantum counterpart—secure multi-party quantum computation (SMPQC) for classical inputs and outputs—in a composable and statistically secure way, even for a single
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Characterization and thermometry of dissipatively stabilized steady states Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-04 G S Grattan, A M Liguori-Schremp, D Rodriguez Perez, E Kapit, W Jones, P Graf
In this work we study the properties of dissipatively stabilized steady states of noisy quantum algorithms, exploring the extent to which they can be well approximated as thermal distributions, and proposing methods to extract the effective temperature T. We study an algorithm called the relaxational quantum eigensolver (RQE), which is one of a family of algorithms that attempt to find ground states
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Heat transport in the quantum Rabi model: universality and ultrastrong coupling effects Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-04 L Magazzù, E Paladino, M Grifoni
Heat transport in a qubit–oscillator junction described by the quantum Rabi model is investigated. Upon variation of temperature, bias on the qubit and the qubit–oscillator coupling strength, a rich variety of effects is identified. For weak coupling to bosonic heat baths, transport is essentially controlled by the qubit–oscillator coupling g which defines a Kondo-like temperature TK(g). At temperatures
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Security of hybrid BB84 with heterodyne detection Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-03 Jasminder S Sidhu, Rocco Maggi, Saverio Pascazio, Cosmo Lupo
Quantum key distribution (QKD) promises everlasting security based on the laws of physics. Most common protocols are grouped into two distinct categories based on the degrees of freedom used to carry information, which can be either discrete or continuous, each presenting unique advantages in either performance, feasibility for near-term implementation, and compatibility with existing telecommunications
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Robustness of diabatic enhancement in quantum annealing Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-02-03 Natasha Feinstein, Ivan Shalashilin, Sougato Bose, P A Warburton
In adiabatic quantum annealing, the speed with which an anneal can be run, while still achieving a high final ground state (GS) fidelity, is dictated by the size of the minimum gap that appears between the ground and first excited state in the annealing spectrum. To avoid the exponential slowdown associated with exponentially closing gaps, diabatic transitions to higher energy levels may be exploited
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Scalable high-dimensional multipartite entanglement with trapped ions Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-31 Harsh Vardhan Upadhyay, Sanket Tripathy, Ting Rei Tan, Baladitya Suri, Athreya Shankar
We propose a protocol for the preparation of generalized Greenberger–Horne–Zeilinger (GHZ) states of N atoms each with d = 3 or 4 internal levels. We generalize the celebrated one-axis twisting (OAT) Hamiltonian for N qubits to qudits by including OAT interactions of equal strengths between every pair of qudit levels, a protocol we call as balanced OAT (BOAT). Analogous to OAT for qubits, we find that
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Towards enhanced precision in thermometry with nonlinear qubits Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-29 Sebastian Deffner
Quantum thermometry refers to the study of measuring ultra-low temperatures in quantum systems. The precision of such a quantum thermometer is limited by the degree to which temperature can be estimated by quantum measurements. More precisely, the maximal precision is given by the inverse of the quantum Fisher information. In the present analysis, we show that quantum thermometers that are described
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Quantum algorithm for polaritonic chemistry based on an exact ansatz Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-28 Samuel Warren, Yuchen Wang, Carlos L Benavides-Riveros, David A Mazziotti
Cavity-modified chemistry uses strong light-matter interactions to modify the electronic properties of molecules in order to enable new physical phenomena such as novel reaction pathways. As cavity chemistry often involves critical regions where configurations become nearly degenerate, the ability to treat multireference problems is crucial to understanding polaritonic systems. In this Letter, we show
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Quantum data encoding as a distinct abstraction layer in the design of quantum circuits Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-28 Gabriele Agliardi, Enrico Prati
Complex quantum circuits are constituted by combinations of quantum subroutines. The computation is possible as long as the quantum data encoding is consistent throughout the circuit. Despite its fundamental importance, the formalization of quantum data encoding has never been addressed systematically so far. We formalize the concept of quantum data encoding, namely the format providing a representation
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Distributing quantum correlations through local operations and classical resources Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-27 Adam G Hawkins, Hannah McAleese, Mauro Paternostro
Distributing quantum correlations to each node of a network is a key aspect of quantum networking. Here, we present a robust, physically motivated protocol by which global quantum correlations, as characterized by the discord, can be distributed to quantum memories using a mixed state of information carriers which possesses only classical correlations. In addition, such distribution is done using only
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Atom interferometer as a freely falling clock for time-dilation measurements Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-22 Albert Roura
Light-pulse atom interferometers based on single-photon transitions are a promising tool for gravitational-wave detection in the mid-frequency band and the search for ultralight dark-matter fields. Here we present a novel measurement scheme that enables their use as freely falling clocks directly measuring relativistic time-dilation effects. The proposal is particularly timely because it can be implemented
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Learning to classify quantum phases of matter with a few measurements Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-20 Mehran Khosrojerdi, Jason L Pereira, Alessandro Cuccoli, Leonardo Banchi
We study the identification of quantum phases of matter, at zero temperature, when only part of the phase diagram is known in advance. Following a supervised learning approach, we show how to use our previous knowledge to construct an observable capable of classifying the phase even in the unknown region. By using a combination of classical and quantum techniques, such as tensor networks, kernel methods
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Conditions for a quadratic quantum speedup in nonlinear transforms with applications to energy contract pricing Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-16 Gabriele Agliardi, Corey O’Meara, Kavitha Yogaraj, Kumar Ghosh, Piergiacomo Sabino, Marina Fernández-Campoamor, Giorgio Cortiana, Juan Bernabé-Moreno, Francesco Tacchino, Antonio Mezzacapo, Omar Shehab
Computing nonlinear functions over multilinear forms is a general problem with applications in risk analysis. For instance in the domain of energy economics, accurate and timely risk management demands for efficient simulation of millions of scenarios, largely benefiting from computational speedups. We develop a novel hybrid quantum–classical algorithm based on polynomial approximation of nonlinear
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Automated quantum system modeling with machine learning Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-16 K Mukherjee, J Schachenmayer, S Whitlock, S Wüster
Despite the complexity of quantum systems in the real world, models with just a few effective many-body states often suffice to describe their quantum dynamics, provided decoherence is accounted for. We show that a machine learning algorithm is able to construct such models, given a straightforward set of quantum dynamics measurements. The effective Hilbert space can be a black box, with variations
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Challenging excited states from adaptive quantum eigensolvers: subspace expansions vs. state-averaged strategies Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-10 Harper R Grimsley, Francesco A Evangelista
The prediction of electronic structure for strongly correlated molecules represents a promising application for near-term quantum computers. Significant attention has been paid to ground state wavefunctions, but excited states of molecules are relatively unexplored. In this work, we consider the adaptive, problem-tailored (ADAPT)-variational quantum eigensolver (VQE) algorithm, a single-reference approach
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Fast, low-loss, all-optical phase modulation in warm rubidium vapour Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-09 William O C Davis, Paul Burdekin, Tabijah Wasawo, Sarah E Thomas, Peter J Mosley, Joshua Nunn, Cameron McGarry
Low-loss high-speed switches are an integral component of future photonic quantum technologies, with applications in state generation, multiplexing, and the implementation of quantum gates. Phase modulation is one method of achieving this switching; however, existing optical phase modulators offer either high bandwidth or low loss—not both. We demonstrate fast (100 MHz bandwidth), low-loss ( 83(2)%
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Dynamical generation and transfer of nonclassical states in strongly interacting light-matter systems in cavities Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-09 Ilia Tutunnikov, Vasil Rokaj, Jianshu Cao, H R Sadeghpour
We propose leveraging strong and ultrastrong light-matter coupling to efficiently generate and exchange nonclassical light and quantum matter states. Two initial conditions are considered: (a) a displaced quadrature-squeezed matter state, and (b) a coherent state in a cavity. In both scenarios, polaritons mediate the dynamical generation and transfer of nonclassical states between light and matter
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Solving an industrially relevant quantum chemistry problem on quantum hardware Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-08 Ludwig Nützel, Alexander Gresch, Lukas Hehn, Lucas Marti, Robert Freund, Alex Steiner, Christian D Marciniak, Timo Eckstein, Nina Stockinger, Stefan Wolf, Thomas Monz, Michael Kühn, Michael J Hartmann
Quantum chemical calculations are among the most promising applications for quantum computing. Implementations of dedicated quantum algorithms on available quantum hardware were so far, however, mostly limited to comparatively simple systems without strong correlations. As such, they can also be addressed by classically efficient single-reference methods. Here we calculate the lowest energy eigenvalue
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Cyclic solid-state quantum battery: thermodynamic characterization and quantum hardware simulation Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-08 Luca Razzoli, Giulia Gemme, Ilia Khomchenko, Maura Sassetti, Henni Ouerdane, Dario Ferraro, Giuliano Benenti
We introduce a cyclic quantum battery QB model, based on an interacting bipartite system, weakly coupled to a thermal bath. The working cycle of the battery consists of four strokes: system thermalization, disconnection of subsystems, ergotropy extraction, and reconnection. The thermal bath acts as a charger in the thermalization stroke, while ergotropy extraction is possible because the ensuing thermal
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Hamiltonian and Liouvillian learning in weakly-dissipative quantum many-body systems Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-08 Tobias Olsacher, Tristan Kraft, Christian Kokail, Barbara Kraus, Peter Zoller
We discuss Hamiltonian and Liouvillian learning for analog quantum simulation from non-equilibrium quench dynamics in the limit of weakly dissipative many-body systems. We present and compare various methods and strategies to learn the operator content of the Hamiltonian and the Lindblad operators of the Liouvillian. We compare different ansätze based on an experimentally accessible ‘learning error’
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Expressive quantum perceptrons for quantum neuromorphic computing Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-08 Rodrigo Araiza Bravo, Taylor L Patti, Khadijeh Najafi, Xun Gao, Susanne F Yelin
Quantum neuromorphic computing (QNC) is a sub-field of quantum machine learning (QML) that capitalizes on inherent system dynamics. As a result, QNC can run on contemporary, noisy quantum hardware and is poised to realize challenging algorithms in the near term. One key issue in QNC is the characterization of the requisite dynamics for ensuring expressive quantum neuromorphic computation. We address
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Time-reversed biphoton source of the double-Λ spontaneous four-wave mixing process Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-07 Wei-Kai Huang, Bongjune Kim, Teng-Jen Shih, Chia-Yu Hsu, Pei-Yu Tu, Tse-Yu Lin, Yong-Fan Chen, Chih-Sung Chuu, Ite A Yu
Utilizing the double-Λ spontaneous four-wave mixing (SFWM) process, the biphoton source generates narrow-linewidth pairs of signal and probe photons. In a medium, the signal photon propagates at nearly the speed of light in a vacuum, while the probe photon propagates as slow light. Typically, signal photons arrive at the detector first and are used as the heralding photons in conventional biphoton
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Detecting unfaithful entanglement by multiple fidelities Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-07 Ruiqi Zhang, Zhaohui Wei
Certifying entanglement for unknown quantum states experimentally is a fundamental problem in quantum computing and quantum physics. Because of being easy to implement, a most popular approach for this problem in modern quantum experiments is detecting target quantum states with fidelity-based entanglement witnesses. Specifically, if the fidelity between a target state and an entangled pure state exceeds
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Profiling quantum circuits for their efficient execution on single- and multi-core architectures Quantum Sci. Technol. (IF 5.6) Pub Date : 2025-01-06 Medina Bandic, Pablo le Henaff, Anabel Ovide, Pau Escofet, Sahar Ben Rached, Santiago Rodrigo, Hans van Someren, Sergi Abadal, Eduard Alarcón, Carmen G Almudever, Sebastian Feld
Application-specific quantum computers offer the most efficient means to tackle problems intractable by classical computers. Realizing these architectures necessitates a deep understanding of quantum circuit properties and their relationship to execution outcomes on quantum devices. Our study aims to perform for the first time a rigorous examination of quantum circuits by introducing graph theory-based
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Coherent and non-unitary errors in ZZ-generated gates Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-30 Thorge Müller, Tobias Stollenwerk, David Headley, Michael Epping, Frank K Wilhelm
Variational algorithms such as the quantum approximate optimization algorithm have attracted attention due to their potential for solving problems using near-term quantum computers. The ZZ interaction typically generates the primitive two-qubit gate in such algorithms applied for a time, typically a variational parameter, γ. Different compilation techniques exist with respect to the implementation
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Distributed quantum machine learning via classical communication Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-30 Kiwmann Hwang, Hyang-Tag Lim, Yong-Su Kim, Daniel K Park, Yosep Kim
Quantum machine learning is emerging as a promising application of quantum computing due to its distinct way of encoding and processing data. It is believed that large-scale quantum machine learning demonstrates substantial advantages over classical counterparts, but a reliable scale-up is hindered by the fragile nature of quantum systems. Here we present an experimentally accessible distributed quantum
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GALIC: hybrid multi-qubitwise pauli grouping for quantum computing measurement Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-30 Matthew X Burns, Chenxu Liu, Samuel Stein, Bo Peng, Karol Kowalski, Ang Li
Observable estimation is a core primitive in NISQ-era algorithms targeting quantum chemistry applications. To reduce the state preparation overhead required for accurate estimation, recent works have proposed various simultaneous measurement schemes to lower estimator variance. Two primary grouping schemes have been proposed: full commutativity (FC) and qubit-wise commutativity (QWC), with no compelling
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Quantum optics with giant atoms in a structured photonic bath Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-30 Luca Leonforte, Xuejian Sun, Davide Valenti, Bernardo Spagnolo, Fabrizio Illuminati, Angelo Carollo, Francesco Ciccarello
We present a general framework to tackle quantum optics problems with giant atoms, i.e. quantum emitters each coupled non-locally to a structured photonic bath (typically a lattice) of any dimension. The theory encompasses the calculation and general properties of Green’s functions, atom-photon bound states, collective master equations and decoherence-free Hamiltonians (DFHs), and is underpinned by
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An operational definition of quantum information scrambling Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-27 Gabriele Lo Monaco, Luca Innocenti, Dario Cilluffo, Diana A Chisholm, Salvatore Lorenzo, G Massimo Palma
Quantum information scrambling (QIS) is a characteristic feature of several quantum systems, ranging from black holes to quantum communication networks. While accurately quantifying QIS is crucial to understanding many such phenomena, common approaches based on the tripartite information have limitations due to the accessibility issues of quantum mutual information, and do not always properly take
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Efficient quantum algorithm for lattice protein folding Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-27 Youle Wang, Xiangzhen Zhou
Predicting a protein’s three-dimensional structure from its primary amino acid sequence constitutes the protein folding problem, a pivotal challenge within computational biology. This task has been identified as a fitting domain for applying quantum annealing, an algorithmic technique posited to be faster than its classical counterparts. Nevertheless, the utility of quantum annealing is intrinsically
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Robust quantum metrology with random Majorana constellations Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-23 Aaron Z Goldberg, Jose R Hervas, Angel S Sanz, Andrei B Klimov, Jaroslav Řeháček, Zdeněk Hradil, Markus Hiekkamäki, Matias Eriksson, Robert Fickler, Gerd Leuchs, Luis L Sánchez-Soto
Even the most classical states are still governed by quantum theory. A number of physical systems can be described by their Majorana constellations of points on the surface of a sphere, where concentrated constellations and highly symmetric distributions correspond to the least and most quantum states, respectively. If these points are chosen randomly, how quantum will the resultant state be, on average
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Quantum data centres: a simulation-based comparative noise analysis Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-23 K Campbell, A Lawey, M Razavi
Quantum data centres (QDCs) could overcome the scalability challenges of modern quantum computers. Single-processor monolithic quantum computers are affected by increased cross talk and difficulty of implementing gates when the number of qubits is increased. In a QDC, multiple quantum processing units (QPUs) are linked together over short distances, allowing the total number of computational qubits
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Highly efficient encoding for job-shop scheduling problems and its application on quantum computers Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-23 Mathias Schmid, Sarah Braun, Rudolf Sollacher, Michael J Hartman
Combinatorial optimization problems are considered to be an application, where quantum computing can have transformative impact. In the industrial context, job shop scheduling problems that aim at finding the optimal schedule for a set of jobs to be run on a set of machines are of immense interest. Here we introduce an efficient encoding of job shop scheduling problems, which requires much fewer bit-strings
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Advantage distillation for quantum key distribution Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-20 Zhenyu Du, Guoding Liu, Xingjian Zhang, Xiongfeng Ma
Quantum key distribution promises information-theoretically secure communication, with data post-processing playing a vital role in extracting secure keys from raw data. While hardware advancements have significantly improved practical implementations, optimizing post-processing techniques offers a cost-effective avenue to enhance performance. Advantage distillation, which extends beyond standard information
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Local ergotropy and its fluctuations across a dissipative quantum phase transition Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-19 G Di Bello, D Farina, D Jansen, C A Perroni, V Cataudella, G De Filippis
We investigate a two-qubit open Rabi model, focusing on local ergotropy-the maximum extractable work by acting solely on the two qubits-within a parameter regime where a Berezinskii–Kosterlitz–Thouless dissipative phase transition occurs. First, we aim to define a protocol for charging, storing, and discharging the two-qubit subsystem, interpreted as the working principle of an open quantum battery
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Equivariant Variational Quantum Eigensolver to detect phase transitions through energy level crossings Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-17 Giulio Crognaletti, Giovanni Di Bartolomeo, Michele Vischi, Luciano Loris Viteritti
Level spectroscopy stands as a powerful method for identifying the transition point that delineates distinct quantum phases. Since each quantum phase exhibits a characteristic sequence of excited states, the crossing of energy levels between low-lying excited states offers a reliable mean to estimate the phase transition point. While approaches like the Variational Quantum Eigensolver are useful for
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Thermodynamic roles of quantum environments: from heat baths to work reservoirs Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-16 Alessandra Colla, Heinz-Peter Breuer
Environments in quantum thermodynamics usually take the role of heat baths. These baths are Markovian, weakly coupled to the system, and initialized in a thermal state. Whenever one of these properties is missing, standard quantum thermodynamics is no longer suitable to treat the thermodynamic properties of the system that result from the interaction with the environment. Using a recently proposed
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Detecting quantum vacuum fluctuations of the electromagnetic field Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-12 Aaron R Malcolm, B Sharmila, Zhi-Wei Wang, Animesh Datta
Quantum vacuum fluctuations of the electromagnetic field result in two signatures on a harmonically trapped charged particle: a shift from the natural trap frequency and generation of quantum coherences. We assess the role of the long-wavelength and rotating-wave approximations (RWAs) in estimating this frequency shift. We estimate the magnitude of the frequency shift using parameters from a single-electron
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Post-measurement pairing quantum key distribution with local optical frequency standard Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-12 Chengfang Ge, Lai Zhou, Jinping Lin, Hua-Lei Yin, Qiang Zeng, Zhiliang Yuan
The idea of post-measurement coincidence pairing simplifies substantially long-distance, repeater-like quantum key distribution (QKD) by eliminating the need for tracking the differential phase of the users’ lasers. However, optical frequency tracking remains necessary and can become a severe burden in future deployment of multi-node quantum networks. Here, we resolve this problem by referencing each
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Dephasing-tolerant quantum sensing for transverse magnetic fields with spin qudits Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-11 Matteo Mezzadri, Luca Lepori, Alessandro Chiesa, Stefano Carretta
We propose a dephasing-tolerant protocol for quantum sensing of transverse magnetic fields which exploits spin qudit sensors with embedded fault-tolerant (FT) quantum error correction. By exploiting longitudinal drives, the transverse field induces logical Rabi oscillations between encoded states, whose frequency is linear in the transverse field to be probed. Numerical simulations show that the present
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Mixing thermal coherent states for precision and range enhancement in quantum thermometry Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-10 Asghar Ullah, M Tahir Naseem, Özgür E Müstecaplıoğlu
The unavoidable interaction between thermal environments and quantum systems typically leads to the degradation of quantum coherence, which can be fought against by reservoir engineering. We propose the realization of a special mixture of thermal coherent states by coupling a thermal bath with a two-level system (TLS) that is longitudinally coupled to a resonator. We find that the state of the resonator
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Quantum phase transition detection via quantum support vector machine Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-09 Youle Wang, Linyun Cao
Unveiling quantum phase transitions (QPTs) is important for characterising physical systems at low temperatures. However, the detection of these transitions is encumbered by significant challenges, especially in the face of the exponential growth in ground state complexity with system scale. The emergence of quantum machine learning has lately gained traction as a promising method for elucidating the
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Emulating multiparticle emitters with pair-sources: digital discovery of a quantum optics building block Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-05 Sören Arlt, Carlos Ruiz-Gonzalez, Mario Krenn
Linear quantum optics is advancing quickly, driven by sources of correlated photon pairs. Multi-photon sources beyond pairs would be a powerful resource, but are a difficult technology to implement. We have discovered a way in which we can combine multiple pair-sources to act analogous to sources of four, six or even eight correlated photons for the creation of highly entangled quantum states and other
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Pseudomode treatment of strong-coupling quantum thermodynamics Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-12-02 Francesco Albarelli, Bassano Vacchini, Andrea Smirne
The treatment of quantum thermodynamic systems beyond weak coupling is of increasing relevance, yet extremely challenging. The evaluation of thermodynamic quantities in strong-coupling regimes requires a nonperturbative knowledge of the bath dynamics, which in turn relies on heavy numerical simulations. To tame these difficulties, considering thermal bosonic baths linearly coupled to the open system
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Extracting work from coherence in a two-mode Bose–Einstein condensate Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-11-29 L A Williamson, F Cerisola, J Anders, Matthew J Davis
We show how work can be extracted from number-state coherence in a two-mode Bose–Einstein condensate. With careful tuning of parameters, a sequence of thermodynamically reversible steps transforms a Glauber coherent state into a thermal state with the same energy probability distribution. The work extracted during this process arises entirely from the removal of quantum coherence. More generally, we
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Driving superconducting qubits into chaos Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-11-28 Jorge Chávez-Carlos, Miguel A Prado Reynoso, Rodrigo G Cortiñas, Ignacio García-Mata, Victor S Batista, Francisco Pérez-Bernal, Diego A Wisniacki, Lea F Santos
Kerr parametric oscillators are potential building blocks for fault-tolerant quantum computers. They can stabilize Kerr-cat qubits, which offer advantages toward the encoding and manipulation of error-protected quantum information. The recent realization of Kerr-cat qubits made use of the nonlinearity of transmon superconducting circuits and a squeezing drive. Increasing nonlinearities can enable faster
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Digital–analog quantum learning on Rydberg atom arrays Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-11-27 Jonathan Z Lu, Lucy Jiao, Kristina Wolinski, Milan Kornjača, Hong-Ye Hu, Sergio Cantu, Fangli Liu, Susanne F Yelin, Sheng-Tao Wang
We propose hybrid digital–analog (DA) learning algorithms on Rydberg atom arrays, combining the potentially practical utility and near-term realizability of quantum learning with the rapidly scaling architectures of neutral atoms. Our construction requires only single-qubit operations in the digital setting and global driving according to the Rydberg Hamiltonian in the analog setting. We perform a
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Planar scanning probe microscopy enables vector magnetic field imaging at the nanoscale Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-11-27 Paul Weinbrenner, Patricia Quellmalz, Christian Giese, Luis Flacke, Manuel Müller, Matthias Althammer, Stephan Geprägs, Rudolf Gross, Friedemann Reinhard
Planar scanning probe microscopy is a recently emerging alternative approach to tip-based scanning probe imaging. It can scan an extended planar sensor, such as a polished bulk diamond doped with magnetic-field-sensitive nitrogen-vacancy (NV) centers, in nanometer-scale proximity of a planar sample. So far, this technique has been limited to optical near-field microscopy and has required nanofabrication
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Quantum-inspired attribute selection algorithms Quantum Sci. Technol. (IF 5.6) Pub Date : 2024-11-25 Diksha Sharma, Parvinder Singh, Atul Kumar
In this study, we propose the use of quantum information gain (QIG) and fidelity as quantum splitting criteria to construct an efficient and balanced quantum decision tree. QIG is a circuit-based criterion in which angle embedding is used to construct a quantum state, which utilizes quantum mutual information to compute the information between a feature and the class attribute. For the fidelity-based