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A de Finetti theorem for quantum causal structures Quantum (IF 5.1) Pub Date : 2025-02-11 Fabio Costa, Jonathan Barrett, Sally Shrapnel
What does it mean for a causal structure to be `unknown'? Can we even talk about `repetitions' of an experiment without prior knowledge of causal relations? And under what conditions can we say that a set of processes with arbitrary, possibly indefinite, causal structure are independent and identically distributed? Similar questions for classical probabilities, quantum states, and quantum channels
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Superpositions of thermalisations in relativistic quantum field theory Quantum (IF 5.1) Pub Date : 2025-02-11 Joshua Foo, Magdalena Zych
Recent results in relativistic quantum information and quantum thermodynamics have independently shown that in the quantum regime, a system may fail to thermalise when subject to quantum-controlled application of the same, single thermalisation channel. For example, an accelerating system with fixed proper acceleration is known to thermalise to an acceleration-dependent temperature, known as the Unruh
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Refining resource estimation for the quantum computation of vibrational molecular spectra through Trotter error analysis Quantum (IF 5.1) Pub Date : 2025-02-11 Dimitar Trenev, Pauline J Ollitrault, Stuart M. Harwood, Tanvi P. Gujarati, Sumathy Raman, Antonio Mezzacapo, Sarah Mostame
Accurate simulations of vibrational molecular spectra are expensive on conventional computers. Compared to the electronic structure problem, the vibrational structure problem with quantum computers is less investigated. In this work we accurately estimate quantum resources, such as number of logical qubits and quantum gates, required for vibrational structure calculations on a programmable quantum
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Convergence and Quantum Advantage of Trotterized MERA for Strongly-Correlated Systems Quantum (IF 5.1) Pub Date : 2025-02-11 Qiang Miao, Thomas Barthel
Strongly-correlated quantum many-body systems are difficult to study and simulate classically. We recently proposed a variational quantum eigensolver (VQE) based on the multiscale entanglement renormalization ansatz (MERA) with tensors constrained to certain Trotter circuits. Here, we determine the scaling of computation costs for various critical spin chains which substantiates a polynomial quantum
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Multipartite entanglement distribution in a topological photonic network Quantum (IF 5.1) Pub Date : 2025-02-10 Juan Zurita, Andrés Agustí Casado, Charles E. Creffield, Gloria Platero
In the ongoing effort towards a scalable quantum computer, multiple technologies have been proposed. Some of them exploit topological materials to process quantum information. In this work, we propose a lattice of photonic cavities with alternating hoppings to create a modified multidomain SSH chain, that is, a sequence of topological insulators made from chains of dimers. A qubit is then coupled to
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Efficient Hamiltonian encoding algorithms for extracting quantum control mechanism as interfering pathway amplitudes in the Dyson series Quantum (IF 5.1) Pub Date : 2025-02-10 Erez Abrams, Michael Kasprzak, Gaurav Bhole, Tak-San Ho, Herschel Rabitz
Hamiltonian encoding is a methodology for revealing the mechanism behind the dynamics governing controlled quantum systems. In this paper, following Mitra and Rabitz [9], we define mechanism via pathways of eigenstates that describe the evolution of the system, where each pathway is associated with a complex-valued amplitude corresponding to a term in the Dyson series. The evolution of the system is
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Quantum complexity phase transitions in monitored random circuits Quantum (IF 5.1) Pub Date : 2025-02-10 Ryotaro Suzuki, Jonas Haferkamp, Jens Eisert, Philippe Faist
Recently, the dynamics of quantum systems that involve both unitary evolution and quantum measurements have attracted attention due to the exotic phenomenon of measurement-induced phase transitions. The latter refers to a sudden change in a property of a state of $n$ qubits, such as its entanglement entropy, depending on the rate at which individual qubits are measured. At the same time, quantum complexity
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Comparative study of quantum error correction strategies for the heavy-hexagonal lattice Quantum (IF 5.1) Pub Date : 2025-02-06 César Benito, Esperanza López, Borja Peropadre, Alejandro Bermudez
Topological quantum error correction is a milestone in the scaling roadmap of quantum computers, which targets circuits with trillions of gates that would allow running quantum algorithms for real-world problems. The square-lattice surface code has become the workhorse to address this challenge, as it poses milder requirements on current devices both in terms of required error rates and small local
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Enhancing Scalability of Quantum Eigenvalue Transformation of Unitary Matrices for Ground State Preparation through Adaptive Finer Filtering Quantum (IF 5.1) Pub Date : 2025-02-06 Erenay Karacan, Yanbin Chen, Christian B. Mendl
Hamiltonian simulation is a domain where quantum computers have the potential to outperform their classical counterparts. One of the main challenges of such quantum algorithms is increasing the system size, which is necessary to achieve meaningful quantum advantage. In this work, we present an approach to improve the scalability of eigenspace filtering for the ground state preparation of a given Hamiltonian
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Metrological Advantages in Seeded and Lossy Nonlinear Interferometers Quantum (IF 5.1) Pub Date : 2025-02-04 Jasper Kranias, Guillaume Thekkadath, Khabat Heshami, Aaron Z. Goldberg
The quantum Fisher information (QFI) bounds the sensitivity of a quantum measurement, heralding the conditions for quantum advantages when compared with classical strategies. Here, we calculate analytical expressions for the QFI of nonlinear interferometers under lossy conditions and with coherent-state seeding. We normalize the results based on the number of photons going through the sample that induces
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Low-Rank Variational Quantum Algorithm for the Dynamics of Open Quantum Systems Quantum (IF 5.1) Pub Date : 2025-02-04 Sara Santos, Xinyu Song, Vincenzo Savona
The simulation of many-body open quantum systems is key to solving numerous outstanding problems in physics, chemistry, material science, and in the development of quantum technologies. Near-term quantum computers may bring considerable advantage for the efficient simulation of their static and dynamical properties, thanks to hybrid quantum-classical variational algorithms to approximate the dynamics
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Theory of Multimode Squeezed Light Generation in Lossy Media Quantum (IF 5.1) Pub Date : 2025-02-04 Denis A. Kopylov, Torsten Meier, Polina R. Sharapova
A unified theoretical approach to describe the properties of multimode squeezed light generated in a lossy medium is presented. This approach is valid for Markovian environments and includes both a model of discrete losses based on the beamsplitter approach and a generalized continuous loss model based on the spatial Langevin equation. For an important class of Gaussian states, we derive master equations
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Tight bounds for antidistinguishability and circulant sets of pure quantum states Quantum (IF 5.1) Pub Date : 2025-02-04 Nathaniel Johnston, Vincent Russo, Jamie Sikora
A set of pure quantum states is said to be antidistinguishable if upon sampling one at random, there exists a measurement to perfectly determine some state that was not sampled. We show that antidistinguishability of a set of $n$ pure states is equivalent to a property of its Gram matrix called $(n-1)$-incoherence, thus establishing a connection with quantum resource theories that lets us apply a wide
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Beyond unital noise in variational quantum algorithms: noise-induced barren plateaus and limit sets Quantum (IF 5.1) Pub Date : 2025-01-30 Phattharaporn Singkanipa, Daniel A. Lidar
Variational quantum algorithms (VQAs) hold much promise but face the challenge of exponentially small gradients. Unmitigated, this barren plateau (BP) phenomenon leads to an exponential training overhead for VQAs. Perhaps the most pernicious are noise-induced barren plateaus (NIBPs), a type of unavoidable BP arising from open system effects, which have so far been shown to exist for unital noise maps
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Distance-preserving stabilizer measurements in hypergraph product codes Quantum (IF 5.1) Pub Date : 2025-01-30 Argyris Giannisis Manes, Jahan Claes
Unlike the surface code, quantum low-density parity-check (QLDPC) codes can have a finite encoding rate, potentially lowering the error correction overhead. However, finite-rate QLDPC codes have nonlocal stabilizers, making it difficult to design stabilizer measurement circuits that are low-depth and do not decrease the effective distance. Here, we demonstrate that a popular family of finite-rate QLDPC
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Fundamental charges for dual-unitary circuits Quantum (IF 5.1) Pub Date : 2025-01-30 Tom Holden-Dye, Lluis Masanes, Arijeet Pal
Dual-unitary quantum circuits have recently attracted attention as an analytically tractable model of many-body quantum dynamics. Consisting of a 1+1D lattice of 2-qudit gates arranged in a 'brickwork' pattern, these models are defined by the constraint that each gate must remain unitary under swapping the roles of space and time. This dual-unitarity restricts the dynamics of local operators in these
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Measurement events relative to temporal quantum reference frames Quantum (IF 5.1) Pub Date : 2025-01-30 Ladina Hausmann, Alexander Schmidhuber, Esteban Castro-Ruiz
The Page-Wootters formalism is a proposal for reconciling the background-dependent, quantum-mechanical notion of time with the background independence of general relativity. However, the physical meaning of this framework remains debated. In this work, we compare two consistent approaches to the Page-Wootters formalism to clarify the operational meaning of evolution and measurements with respect to
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Designing open quantum systems with known steady states: Davies generators and beyond Quantum (IF 5.1) Pub Date : 2025-01-28 Jinkang Guo, Oliver Hart, Chi-Fang Chen, Aaron J. Friedman, Andrew Lucas
We provide a systematic framework for constructing generic models of nonequilibrium quantum dynamics with a target stationary (mixed) state. Our framework identifies (almost) all combinations of Hamiltonian and dissipative dynamics that relax to a steady state of interest, generalizing the Davies’ generator for dissipative relaxation at finite temperature to nonequilibrium dynamics targeting arbitrary
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Multiplexed Quantum Communication with Surface and Hypergraph Product Codes Quantum (IF 5.1) Pub Date : 2025-01-28 Shin Nishio, Nicholas Connolly, Nicolò Lo Piparo, William John Munro, Thomas Rowan Scruby, Kae Nemoto
Connecting multiple processors via quantum interconnect technologies could help overcome scalability issues in single-processor quantum computers. Transmission via these interconnects can be performed more efficiently using quantum multiplexing, where information is encoded in high-dimensional photonic degrees of freedom. We explore the effects of multiplexing on logical error rates in surface codes
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A thermodynamically consistent approach to the energy costs of quantum measurements Quantum (IF 5.1) Pub Date : 2025-01-28 Camille L Latune, Cyril Elouard
Considering a general microscopic model for a quantum measuring apparatus comprising a quantum probe coupled to a thermal bath, we analyze the energetic resources necessary for the realization of a quantum measurement, which includes the creation of system-apparatus correlations, the irreversible transition to a statistical mixture of definite outcomes, and the apparatus resetting. Crucially, we do
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On the simulation of quantum multimeters Quantum (IF 5.1) Pub Date : 2025-01-27 Andreas Bluhm, Leevi Leppäjärvi, Ion Nechita
In the quest for robust and universal quantum devices, the notion of simulation plays a crucial role, both from a theoretical and from an applied perspective. In this work, we go beyond the simulation of quantum channels and quantum measurements, studying what it means to simulate a collection of measurements, which we call a multimeter. To this end, we first explicitly characterize the completely
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Color code decoder with improved scaling for correcting circuit-level noise Quantum (IF 5.1) Pub Date : 2025-01-27 Seok-Hyung Lee, Andrew Li, Stephen D. Bartlett
Two-dimensional color codes are a promising candidate for fault-tolerant quantum computing, as they have high encoding rates, transversal implementation of logical Clifford gates, and resource-efficient magic state preparation schemes. However, decoding color codes presents a significant challenge due to their structure, where elementary errors violate three checks instead of just two (a key feature
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Relational dynamics and Page-Wootters formalism in group field theory Quantum (IF 5.1) Pub Date : 2025-01-27 Andrea Calcinari, Steffen Gielen
Group field theory posits that spacetime is emergent and is hence defined without any background notion of space or time; dynamical questions are formulated in relational terms, in particular using (scalar) matter degrees of freedom as time. Unlike in canonical quantisation of gravitational systems, there is no obvious notion of coordinate transformations or constraints, and established quantisation
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Security of differential phase shift QKD from relativistic principles Quantum (IF 5.1) Pub Date : 2025-01-27 Martin Sandfuchs, Marcus Haberland, V. Vilasini, Ramona Wolf
The design of quantum protocols for secure key generation poses many challenges: On the one hand, they need to be practical concerning experimental realisations. On the other hand, their theoretical description must be simple enough to allow for a security proof against all possible attacks. Often, these two requirements are in conflict with each other, and the differential phase shift (DPS) QKD protocol
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Symmetry protected topological phases under decoherence Quantum (IF 5.1) Pub Date : 2025-01-23 Jong Yeon Lee, Yi-Zhuang You, Cenke Xu
We investigate mixed states exhibiting nontrivial topological features, focusing on symmetry-protected topological (SPT) phases under various types of decoherence. Our findings demonstrate that these systems can retain topological information from the SPT ground state despite decoherence. In the ''doubled Hilbert space,'' we define symmetry-protected topological ensembles (SPT ensembles) and examine
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Optimizing Circuit Reusing and its Application in Randomized Benchmarking Quantum (IF 5.1) Pub Date : 2025-01-23 Zhuo Chen, Guoding Liu, Xiongfeng Ma
Quantum learning tasks often leverage randomly sampled quantum circuits to characterize unknown systems. An efficient approach known as ``circuit reusing,'' where each circuit is executed multiple times, reduces the cost compared to implementing new circuits. This work investigates the optimal reusing times that minimizes the variance of measurement outcomes for a given experimental cost. We establish
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Streaming quantum state purification Quantum (IF 5.1) Pub Date : 2025-01-21 Andrew M. Childs, Honghao Fu, Debbie Leung, Zhi Li, Maris Ozols, Vedang Vyas
Quantum state purification is the task of recovering a nearly pure copy of an unknown pure quantum state using multiple noisy copies of the state. This basic task has applications to quantum communication over noisy channels and quantum computation with imperfect devices, but has only been studied previously for the case of qubits. We derive an efficient purification procedure based on the swap test
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Linear gate bounds against natural functions for position-verification Quantum (IF 5.1) Pub Date : 2025-01-21 Vahid Asadi, Richard Cleve, Eric Culf, Alex May
A quantum position-verification scheme attempts to verify the spatial location of a prover. The prover is issued a challenge with quantum and classical inputs and must respond with appropriate timings. We consider two well-studied position-verification schemes known as $f$-routing and $f$-BB84. Both schemes require an honest prover to locally compute a classical function $f$ of inputs of length $n$
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Imperfect quantum networks with tailored resource states Quantum (IF 5.1) Pub Date : 2025-01-21 Maria Flors Mor-Ruiz, Julius Wallnöfer, Wolfgang Dür
Entanglement-based quantum networks exhibit a unique flexibility in the choice of entangled resource states that are then locally manipulated by the nodes to fulfill any request in the network. Furthermore, this manipulation is not uniquely defined and thus can be optimized. We tailor the adaptation of the resource state or pre-established entanglement to achieve bipartite communication in an imperfect
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Breaking barriers in two-party quantum cryptography via stochastic semidefinite programming Quantum (IF 5.1) Pub Date : 2025-01-20 Akshay Bansal, Jamie Sikora
In the last two decades, there has been much effort in finding secure protocols for two-party cryptographic tasks. It has since been discovered that even with quantum mechanics, many such protocols are limited in their security promises. In this work, we use stochastic selection, an idea from stochastic programming, to circumvent such limitations. For example, we find a way to switch between bit commitment
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Bipartite polygon models: entanglement classes and their nonlocal behaviour Quantum (IF 5.1) Pub Date : 2025-01-20 Mayalakshmi Kolangatt, Thigazholi Muruganandan, Sahil Gopalkrishna Naik, Tamal Guha, Manik Banik, Sutapa Saha
Hardy's argument constitutes an elegantly logical test for identifying nonlocal features of multipartite correlations. In this paper, we investigate Hardy's nonlocal behavior within a broad class of operational theories, including the qubit state space as a specific case. Specifically, we begin by examining a wider range of operational models with state space descriptions in the form of regular polygons
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Sparse Blossom: correcting a million errors per core second with minimum-weight matching Quantum (IF 5.1) Pub Date : 2025-01-20 Oscar Higgott, Craig Gidney
In this work, we introduce a fast implementation of the minimum-weight perfect matching (MWPM) decoder, the most widely used decoder for several important families of quantum error correcting codes, including surface codes. Our algorithm, which we call sparse blossom, is a variant of the blossom algorithm which directly solves the decoding problem relevant to quantum error correction. Sparse blossom
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Hexagons govern three-qubit contextuality Quantum (IF 5.1) Pub Date : 2025-01-20 Metod Saniga, Frédéric Holweck, Colm Kelleher, Axel Muller, Alain Giorgetti, Henri de Boutray
Split Cayley hexagons of order two are distinguished finite geometries living in the three-qubit symplectic polar space in two different forms, called classical and skew. Although neither of the two yields observable-based contextual configurations of their own, $classically$-embedded copies are found to fully encode contextuality properties of the most prominent three-qubit contextual configurations
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Private and Robust States for Distributed Quantum Sensing Quantum (IF 5.1) Pub Date : 2025-01-15 Luís Bugalho, Majid Hassani, Yasser Omar, Damian Markham
Distributed quantum sensing enables the estimation of multiple parameters encoded in spatially separated probes. While traditional quantum sensing is often focused on estimating a single parameter with maximum precision, distributed quantum sensing seeks to estimate some function of multiple parameters that are only locally accessible for each party involved. In such settings, it is natural to not
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Efficient Learning of Long-Range and Equivariant Quantum Systems Quantum (IF 5.1) Pub Date : 2025-01-15 Štěpán Šmíd, Roberto Bondesan
In this work, we consider a fundamental task in quantum many-body physics – finding and learning ground states of quantum Hamiltonians and their properties. Recent works have studied the task of predicting the ground state expectation value of sums of geometrically local observables by learning from data. For short-range gapped Hamiltonians, a sample complexity that is logarithmic in the number of
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Can QBism exist without Q? Morphophoric measurements in generalised probabilistic theories Quantum (IF 5.1) Pub Date : 2025-01-15 Anna Szymusiak, Wojciech Słomczyński
In a Generalised Probabilistic Theory (GPT) equipped additionally with some extra geometric structure we define the morphophoric measurements as those for which the measurement map sending states to distributions of the measurement results is a similarity. In the quantum case, morphophoric measurements generalise the notion of a 2-design POVM, thus in particular that of a SIC-POVM. We show that the
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Response to “The measurement postulates of quantum mechanics are not redundant” Quantum (IF 5.1) Pub Date : 2025-01-14 Lluís Masanes, Thomas D. Galley, Markus P. Müller
Adrian Kent has recently presented a critique [1] of our paper [2] in which he claims to refute our main result: the measurement postulates of quantum mechanics can be derived from the rest of postulates, once we assume that the set of mixed states of a finite-dimensional Hilbert space is finite-dimensional. To construct his argument, Kent considers theories resulting from supplementing quantum mechanics
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Lower bounds for quantum-inspired classical algorithms via communication complexity Quantum (IF 5.1) Pub Date : 2025-01-14 Nikhil S. Mande, Changpeng Shao
Quantum-inspired classical algorithms provide us with a new way to understand the computational power of quantum computers for practically-relevant problems, especially in machine learning. In the past several years, numerous efficient algorithms for various tasks have been found, while an analysis of lower bounds is still missing. Using communication complexity, in this work we propose the first method
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Recursive Quantum Relaxation for Combinatorial Optimization Problems Quantum (IF 5.1) Pub Date : 2025-01-15 Ruho Kondo, Yuki Sato, Rudy Raymond, Naoki Yamamoto
Quantum optimization methods use a continuous degree-of-freedom of quantum states to heuristically solve combinatorial problems, such as the MAX-CUT problem, which can be attributed to various NP-hard combinatorial problems. This paper shows that some existing quantum optimization methods can be unified into a solver to find the binary solution which is most likely measured from the optimal quantum
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Efficient discrimination between real and complex quantum theories Quantum (IF 5.1) Pub Date : 2025-01-15 Josep Batle, Tomasz Białecki, Tomasz Rybotycki, Jakub Tworzydło, Adam Bednorz
We improve the test to show the impossibility of a quantum theory based on real numbers by a larger ratio of complex-to-real bound on a Bell-type parameter. In contrast to previous theoretical and experimental proposals the test requires three settings for the parties $A$ and $C$, but also six settings for the middle party $B$, assuming separability of the sources. The bound we found for this symmetric
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A graph-state based synthesis framework for Clifford isometries Quantum (IF 5.1) Pub Date : 2025-01-14 Timothée Goubault de Brugière, Simon Martiel, Christophe Vuillot
We tackle the problem of Clifford isometry compilation, i.e, how to synthesize a Clifford isometry into an executable quantum circuit. We propose a simple framework for synthesis that only exploits the elementary properties of the Clifford group and one equation of the symplectic group. We highlight the versatility of our framework by showing that several normal forms of the literature are natural
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Unlocking Heisenberg Sensitivity with Sequential Weak Measurement Preparation Quantum (IF 5.1) Pub Date : 2025-01-14 T. B. Lantaño, Dayou Yang, K. M. R. Audenaert, S. F. Huelga, M. B. Plenio
We propose a state preparation protocol based on sequential measurements of a central spin coupled with a spin ensemble, and investigate the usefulness of the generated multi-spin states for quantum enhanced metrology. Our protocol is shown to generate highly entangled spin states, devoid of the necessity for non-linear spin interactions. The metrological sensitivity of the resulting state surpasses
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A hierarchy of semidefinite programs for generalised Einstein-Podolsky-Rosen scenarios Quantum (IF 5.1) Pub Date : 2025-01-14 Matty J. Hoban, Tom Drescher, Ana Belén Sainz
Correlations in Einstein-Podolsky-Rosen (EPR) scenarios, captured by $assemblages$ of unnormalised quantum states, have recently caught the attention of the community, both from a foundational and an information-theoretic perspective. The set of quantum-realisable assemblages, or abbreviated to quantum assemblages, are those that arise from multiple parties performing local measurements on a shared
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Out-of-time-ordered correlators of mean-field bosons via Bogoliubov theory Quantum (IF 5.1) Pub Date : 2025-01-13 Marius Lemm, Simone Rademacher
Quantum many-body chaos concerns the scrambling of quantum information among large numbers of degrees of freedom. It rests on the prediction that out-of-time-ordered correlators (OTOCs) of the form $\langle [A(t),B]^2\rangle$ can be connected to classical symplectic dynamics. We rigorously prove a variant of this correspondence principle for mean-field bosons. We show that the $N\to\infty$ limit of
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Des-q: a quantum algorithm to provably speedup retraining of decision trees Quantum (IF 5.1) Pub Date : 2025-01-13 Niraj Kumar, Romina Yalovetzky, Changhao Li, Pierre Minssen, Marco Pistoia
Decision trees are widely adopted machine learning models due to their simplicity and explainability. However, as training data size grows, standard methods become increasingly slow, scaling polynomially with the number of training examples. In this work, we introduce Des-q, a novel quantum algorithm to construct and retrain decision trees for regression and binary classification tasks. Assuming the
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Modeling Short-Range Microwave Networks to Scale Superconducting Quantum Computation Quantum (IF 5.1) Pub Date : 2025-01-08 Nicholas LaRacuente, Kaitlin N. Smith, Poolad Imany, Kevin L. Silverman, Frederic T. Chong
A core challenge for superconducting quantum computers is to scale up the number of qubits in each processor without increasing noise or cross-talk. Distributed quantum computing across small qubit arrays, known as chiplets, can address these challenges in a scalable manner. We propose a chiplet architecture over microwave links with potential to exceed monolithic performance on near-term hardware
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Device-independent uncloneable encryption Quantum (IF 5.1) Pub Date : 2025-01-08 Srijita Kundu, Ernest Y.-Z. Tan
Uncloneable encryption, first introduced by Broadbent and Lord (TQC 2020) is a quantum encryption scheme in which a quantum ciphertext cannot be distributed between two non-communicating parties such that, given access to the decryption key, both parties cannot learn the underlying plaintext. In this work, we introduce a variant of uncloneable encryption in which several possible decryption keys can
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No quantum solutions to linear constraint systems in odd dimension from Pauli group and diagonal Cliffords Quantum (IF 5.1) Pub Date : 2025-01-08 Markus Frembs, Cihan Okay, Ho Yiu Chung
Linear constraint systems (LCS) have proven to be a surprisingly prolific tool in the study of non-classical correlations and various related issues in quantum foundations. Many results are known for the Boolean case, yet the generalisation to systems of odd dimension is largely open. In particular, it is not known whether there exist LCS in odd dimension, which admit finite-dimensional quantum, but
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Cryptomite: A versatile and user-friendly library of randomness extractors Quantum (IF 5.1) Pub Date : 2025-01-08 Cameron Foreman, Richie Yeung, Alec Edgington, Florian J. Curchod
We present $\texttt{Cryptomite}$, a Python library of randomness extractor implementations. The library offers a range of two-source, seeded and deterministic randomness extractors, together with parameter calculation modules, making it easy to use and suitable for a variety of applications. We also present theoretical results, including new extractor constructions and improvements to existing extractor
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Ultratight confinement of atoms in a Rydberg empowered optical lattice Quantum (IF 5.1) Pub Date : 2025-01-08 Mohammadsadegh Khazali
Optical lattices serve as fundamental building blocks for atomic quantum technology. However, the scale and resolution of these lattices are diffraction-limited to the light wavelength. In conventional lattices, achieving tight confinement of single sites requires high laser intensity, which unfortunately leads to reduced coherence due to increased scattering. This article presents a novel approach
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Fast algorithms for classical specifications of stabiliser states and Clifford gates Quantum (IF 5.1) Pub Date : 2025-01-08 Nadish de Silva, Wilfred Salmon, Ming Yin
The stabiliser formalism plays a central role in quantum computing, error correction, and fault tolerance. Conversions between and verifications of different specifications of stabiliser states and Clifford gates are important components of many classical algorithms in quantum information, e.g. for gate synthesis, circuit optimisation, and simulating quantum circuits. These core functions are also
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Characterization of errors in a CNOT between surface code patches Quantum (IF 5.1) Pub Date : 2024-12-27 Bálint Domokos, Áron Márton, János K. Asbóth
As current experiments already realize small quantum circuits on error corrected qubits, it is important to fully understand the effect of physical errors on the logical error channels of these fault-tolerant circuits. Here, we investigate a lattice-surgery-based CNOT operation between two surface code patches under phenomenological error models. (i) For two-qubit logical Pauli measurements – the elementary
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Strategies for implementing quantum error correction in molecular rotation Quantum (IF 5.1) Pub Date : 2024-12-27 Brandon J. Furey, Zhenlin Wu, Mariano Isaza-Monsalve, Stefan Walser, Elyas Mattivi, René Nardi, Philipp Schindler
The rotation of trapped molecules offers a promising platform for quantum technologies and quantum information processing. In parallel, quantum error correction codes that can protect quantum information encoded in rotational states of a single molecule have been developed. These codes are currently an abstract concept, as no implementation strategy is yet known. Here, we present a step towards experimental
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Quantum Phase Estimation by Compressed Sensing Quantum (IF 5.1) Pub Date : 2024-12-27 Changhao Yi, Cunlu Zhou, Jun Takahashi
As a signal recovery algorithm, compressed sensing is particularly effective when the data has low complexity and samples are scarce, which aligns natually with the task of quantum phase estimation (QPE) on early fault-tolerant quantum computers. In this work, we present a new Heisenberg-limited, robust QPE algorithm based on compressed sensing, which requires only sparse and discrete sampling of times
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Approximate Contraction of Arbitrary Tensor Networks with a Flexible and Efficient Density Matrix Algorithm Quantum (IF 5.1) Pub Date : 2024-12-27 Linjian Ma, Matthew Fishman, Edwin Miles Stoudenmire, Edgar Solomonik
Tensor network contractions are widely used in statistical physics, quantum computing, and computer science. We introduce a method to efficiently approximate tensor network contractions using low-rank approximations, where each intermediate tensor generated during the contractions is approximated as a low-rank binary tree tensor network. The proposed algorithm has the flexibility to incorporate a large
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Joint-measurability and quantum communication with untrusted devices Quantum (IF 5.1) Pub Date : 2024-12-23 Michele Masini, Marie Ioannou, Nicolas Brunner, Stefano Pironio, Pavel Sekatski
Photon loss represents a major challenge for the implementation of quantum communication protocols with untrusted devices, e.g. in the device-independent (DI) or semi-DI approaches. Determining critical loss thresholds is usually done in case-by-case studies. In the present work, we develop a general framework for characterizing the admissible levels of loss and noise in a wide range of scenarios and
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QOSST: A Highly-Modular Open Source Platform for Experimental Continuous-Variable Quantum Key Distribution Quantum (IF 5.1) Pub Date : 2024-12-23 Yoann Piétri, Matteo Schiavon, Valentina Marulanda Acosta, Baptiste Gouraud, Luis Trigo Vidarte, Philippe Grangier, Amine Rhouni, Eleni Diamanti
Quantum Key Distribution (QKD) enables secret key exchange between two remote parties with information-theoretic security rooted in the laws of quantum physics. Encoding key information in continuous variables (CV), such as the values of quadrature components of coherent states of light, brings implementations much closer to standard optical communication systems, but this comes at the price of significant
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Enhanced Entanglement in the Measurement-Altered Quantum Ising Chain Quantum (IF 5.1) Pub Date : 2024-12-23 Alessio Paviglianiti, Xhek Turkeshi, Marco Schirò, Alessandro Silva
Understanding the influence of measurements on the properties of many-body systems is a fundamental problem in quantum mechanics and for quantum technologies. This paper explores how a finite density of stochastic local measurement modifies a given state’s entanglement structure. Considering various measurement protocols, we explore the typical quantum correlations of their associated projected ensembles
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Efficient tensor networks for control-enhanced quantum metrology Quantum (IF 5.1) Pub Date : 2024-12-18 Qiushi Liu, Yuxiang Yang
Optimized quantum control can enhance the performance and noise resilience of quantum metrology. However, the optimization quickly becomes intractable when multiple control operations are applied sequentially. In this work, we propose efficient tensor network algorithms for optimizing strategies of quantum metrology enhanced by a long sequence of control operations. Our approach covers a general and
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Heralded Optical Entanglement Generation via the Graph Picture of Linear Quantum Networks Quantum (IF 5.1) Pub Date : 2024-12-18 Seungbeom Chin, Marcin Karczewski, Yong-Su Kim
Non-destructive heralded entanglement with photons is a valuable resource for quantum information processing. However, they generally entail ancillary particles and modes that amplify the circuit intricacy. To address this challenge, a recent work [16] introduced a graph approach for creating multipartite entanglements with boson subtractions. Nonetheless, it remains an essential intermediate step