From quantum-journal.org
Ground and Excited States from Ensemble Variational Principles
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Lexin Ding, Cheng-Lin Hong, and Christian Schilling, Quantum 8, 1525 (2024). The extension of the Rayleigh-Ritz variational principle to ensemble states $\rho_{\mathbf{w}}\equiv\sum_k w_k |\Psi_k\rangle \langle\Psi_k|$ with fixed weights $w_k$ lies ultimately at the hear…
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15h ago
From quantum-journal.org
Gradients and frequency profiles of quantum re-uploading models
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Alice Barthe and Adrián Pérez-Salinas, Quantum 8, 1523 (2024). Quantum re-uploading models have been extensively investigated as a form of machine learning within the context of variational quantum algorithms. Their trainability and expressivity are not…
#paper #quantum #research #OpenScience
18h ago
From quantum-journal.org
Anomalous Floquet Phases. A resonance phenomena
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Álvaro Gómez-León, Quantum 8, 1522 (2024). Floquet topological phases emerge when systems are periodically driven out-of-equilibrium. They gained attention due to their external control, which allows to simulate a wide variety of sta…
on Wed, 4PM
From quantum-journal.org
Photon-number moments and cumulants of Gaussian states
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Yanic Cardin and Nicolás Quesada, Quantum 8, 1521 (2024). We develop closed-form expressions for the moments and cumulants of Gaussian states when measured in the photon-number basis. We express the photon-number moments of a Gaussian state in term…
on Wed, 2PM
From quantum-journal.org
Scattering wave packets of hadrons in gauge theories: Preparation on a quantum computer
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Zohreh Davoudi, Chung-Chun Hsieh, and Saurabh V. Kadam, Quantum 8, 1520 (2024). Quantum simulation holds promise of enabling a complete description of high-energy scattering processes rooted in gauge theories of the Standard Model. A first step in such simulations is pr…
on Mon, 2PM
From quantum-journal.org
Phase-space negativity as a computational resource for quantum kernel methods
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Ulysse Chabaud, Roohollah Ghobadi, Salman Beigi, and Saleh Rahimi-Keshari, Quantum 8, 1519 (2024). Quantum kernel methods are a proposal for achieving quantum computational advantage in machine learning. They are based on a hybrid classical-quantum computation where a function called the…
on Nov 7
From quantum-journal.org
Asymmetry activation and its relation to coherence under permutation operation
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Masahito Hayashi, Quantum 8, 1517 (2024). A Dicke state and its decohered state are invariant for permutation. However, when another qubits state to each of them is attached, the whole state is not invariant for permutation, and has…
on Nov 7
From quantum-journal.org
Epistemic Boundaries and Quantum Uncertainty: What Local Observers Can (Not) Predict
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Johannes Fankhauser, Quantum 8, 1518 (2024). One of quantum theory's salient features is its apparent indeterminism, i.e. measurement outcomes are typically probabilistic. We formally define and address whether this uncertainty is unav…
on Nov 7
From quantum-journal.org
Maximal Elements of Quantum Communication
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Teiko Heinosaari and Oskari Kerppo, Quantum 8, 1515 (2024). A prepare-and-measure scenario is naturally described by a communication matrix that collects all conditional outcome probabilities of the scenario into a row-stochastic matrix. The set of a…
on Nov 7
From quantum-journal.org
Benchmarking a trapped-ion quantum computer with 30 qubits
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Jwo-Sy Chen, Erik Nielsen, Matthew Ebert, Volkan Inlek, Kenneth Wright, Vandiver Chaplin, Andrii Maksymov, Eduardo Páez, Amrit Poudel, Peter Maunz, and John Gamble, Quantum 8, 1516 (2024). Quantum computers are rapidly becoming more capable, with dramatic increases in both qubit count [1] and...
on Nov 7
From quantum-journal.org
Network-Device-Independent Certification of Causal Nonseparability
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Hippolyte Dourdent, Alastair A. Abbott, Ivan Šupić, and Cyril Branciard, Quantum 8, 1514 (2024). Causal nonseparability is the property underlying quantum processes incompatible with a definite causal order. So far it has remained a central open question as to whether any process with a…
on Oct 30
From quantum-journal.org
Universal quantum processors in spin systems via robust local pulse sequences
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Matteo Votto, Johannes Zeiher, and Benoît Vermersch, Quantum 8, 1513 (2024). We propose a protocol to realize quantum simulation and computation in spin systems with long-range interactions. Our approach relies on the local addressing of single spins with external fi…
on Oct 29
From quantum-journal.org
Comment on “Multivariable quantum signal processing (M-QSP): prophecies of the two-headed oracle”
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Hitomi Mori, Kaoru Mizuta, and Keisuke Fujii, Quantum 8, 1512 (2024). Multivariable Quantum Signal Processing (M-QSP) [1] is expected to provide an efficient means to handle polynomial transformations of multiple variables simultaneously. However, we identifie…
on Oct 29
From quantum-journal.org
Hardness results for decoding the surface code with Pauli noise
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Alex Fischer and Akimasa Miyake, Quantum 8, 1511 (2024). Real quantum computers will be subject to complicated, qubit-dependent noise, instead of simple noise such as depolarizing noise with the same strength for all qubits. We can do quantum erro…
on Oct 28
From quantum-journal.org
Deterministic Bethe state preparation
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David Raveh and Rafael I. Nepomechie, Quantum 8, 1510 (2024). We present an explicit quantum circuit that prepares an arbitrary $U(1)$-eigenstate on a quantum computer, including the exact eigenstates of the spin-$1/2 XXZ$ quantum spin chain with either op…
on Oct 24
From quantum-journal.org
Limitations for Quantum Algorithms to Solve Turbulent and Chaotic Systems
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Dylan Lewis, Stephan Eidenbenz, Balasubramanya Nadiga, and Yiğit Subaşı, Quantum 8, 1509 (2024). We investigate the limitations of quantum computers for solving nonlinear dynamical systems. In particular, we tighten the worst-case bounds of the quantum Carleman linearisation (QCL) algor…
on Oct 24
From quantum-journal.org
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Pablo Arrighi, Amélia Durbec, and Matt Wilson, Quantum 8, 1508 (2024). The formalism of quantum theory over discrete systems is extended in two significant ways. First, quantum evolutions are generalized to act over entire network configurations, so that nodes…
on Oct 23
From quantum-journal.org
Quantum Universally Composable Oblivious Linear Evaluation
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Manuel B. Santos, Paulo Mateus, and Chrysoula Vlachou, Quantum 8, 1507 (2024). Oblivious linear evaluation is a generalization of oblivious transfer, whereby two distrustful parties obliviously compute a linear function, $f (x) = ax + b$, i.e., each one provides their in…
on Oct 23
From quantum-journal.org
Decoding quantum color codes with MaxSAT
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Lucas Berent, Lukas Burgholzer, Peter-Jan H.S. Derks, Jens Eisert, and Robert Wille, Quantum 8, 1506 (2024). In classical computing, error-correcting codes are well established and are ubiquitous both in theory and practical applications. For quantum computing, error-correction is essential as well…
on Oct 23
From quantum-journal.org
Programmable adiabatic demagnetization for systems with trivial and topological excitations
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Anne Matthies, Mark Rudner, Achim Rosch, and Erez Berg, Quantum 8, 1505 (2024). We propose a simple, robust protocol to prepare a low-energy state of an arbitrary Hamiltonian on a quantum computer or programmable quantum simulator. The protocol is inspired by the adiaba…
on Oct 23
From quantum-journal.org
Option pricing under stochastic volatility on a quantum computer
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Guoming Wang and Angus Kan, Quantum 8, 1504 (2024). We develop quantum algorithms for pricing Asian and barrier options under the Heston model, a popular stochastic volatility model, and estimate their costs, in terms of T-count, T-depth and…
on Oct 23
From quantum-journal.org
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Ioannis Kolotouros and Petros Wallden, Quantum 8, 1503 (2024). Hybrid quantum-classical algorithms appear to be the most promising approach for near-term quantum applications. An important bottleneck is the classical optimization loop, where the multipl…
on Oct 22
From quantum-journal.org
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M. Emre Sahin, Benjamin C. B. Symons, Pushpak Pati, Fayyaz Minhas, Declan Millar, Maria Gabrani, Stefano Mensa, and Jan Lukas Robertus, Quantum 8, 1502 (2024). Quantum machine learning with quantum kernels for classification problems is a growing area of research. Recently, quantum kernel...
on Oct 18
From quantum-journal.org
Quantum Locally Testable Code with Constant Soundness
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Andrew Cross, Zhiyang He, Anand Natarajan, Mario Szegedy, and Guanyu Zhu, Quantum 8, 1501 (2024). In this paper, we present two constructions of quantum locally testable codes (QLTC) with constant soundness. In the first approach, we introduce an operation called check product, and show…
on Oct 18
From quantum-journal.org
Resource Efficient Boolean Function Solver on Quantum Computer
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Xiang Li, Hanxiang Shen, Weiguo Gao, and Yingzhou Li, Quantum 8, 1500 (2024). Nonlinear boolean equation systems play an important role in a wide range of applications. Grover's algorithm is one of the best-known quantum search algorithms in solving the nonlinear bool…
on Oct 10
From quantum-journal.org
Decoding algorithms for surface codes
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Antonio deMarti iOlius, Patricio Fuentes, Román Orús, Pedro M. Crespo, and Josu Etxezarreta Martinez, Quantum 8, 1498 (2024). Quantum technologies have the potential to solve certain computationally hard problems with polynomial or super-polynomial speedups when compared to classical methods....
on Oct 10
From quantum-journal.org
Quantum teleportation implies symmetry-protected topological order
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Yifan Hong, David T. Stephen, and Aaron J. Friedman, Quantum 8, 1499 (2024). We constrain a broad class of teleportation protocols using insights from locality. In the "standard" teleportation protocols we consider, all outcome-dependent unitaries are Pauli operators…
on Oct 10
From quantum-journal.org
Iteration Complexity of Variational Quantum Algorithms
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Vyacheslav Kungurtsev, Georgios Korpas, Jakub Marecek, and Elton Yechao Zhu, Quantum 8, 1495 (2024). There has been much recent interest in near-term applications of quantum computers, i.e., using quantum circuits that have short decoherence times due to hardware limitations. Variational qu…
on Oct 10
From quantum-journal.org
Implementing any Linear Combination of Unitaries on Intermediate-term Quantum Computers
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Shantanav Chakraborty, Quantum 8, 1496 (2024). We develop three new methods to implement any Linear Combination of Unitaries (LCU), a powerful quantum algorithmic tool with diverse applications. While the standard LCU procedure requires…
on Oct 10
From quantum-journal.org
Quantum lozenge tiling and entanglement phase transition
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Zhao Zhang and Israel Klich, Quantum 8, 1497 (2024). While volume violation of area law has been exhibited in several quantum spin chains, the construction of a corresponding ground state in higher dimensions, entangled in more than one direct…
on Oct 10
From quantum-journal.org
Branching States as The Emergent Structure of a Quantum Universe
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Akram Touil, Fabio Anza, Sebastian Deffner, and James P. Crutchfield, Quantum 8, 1494 (2024). Quantum Darwinism builds on decoherence theory to explain the emergence of classical behavior in a fundamentally quantum universe. Within this framework we prove two crucial insights about t…
on Oct 10
From quantum-journal.org
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Teague Tomesh, Nicholas Allen, Daniel Dilley, and Zain Saleem, Quantum 8, 1493 (2024). The computational capabilities of near-term quantum computers are limited by the noisy execution of gate operations and a limited number of physical qubits. Hybrid variational algorithms are…
on Oct 4
From quantum-journal.org
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Roberto Rubboli, Ryuji Takagi, and Marco Tomamichel, Quantum 8, 1492 (2024). We prove that the stabilizer fidelity is multiplicative for the tensor product of an arbitrary number of single-qubit states. We also show that the relative entropy of magic becomes additive…
on Oct 4
From quantum-journal.org
Differentiating and Integrating ZX Diagrams with Applications to Quantum Machine Learning
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Quanlong Wang, Richie Yeung, and Mark Koch, Quantum 8, 1491 (2024). ZX-calculus has proved to be a useful tool for quantum technology with a wide range of successful applications. Most of these applications are of an algebraic nature. However, other tasks th…
on Oct 4
From quantum-journal.org
Repeated measurements on non-replicable systems and their consequences for Unruh-DeWitt detectors
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Nicola Pranzini, Guillermo García-Pérez, Esko Keski-Vakkuri, and Sabrina Maniscalco, Quantum 8, 1490 (2024). The Born rule describes the probability of obtaining an outcome when measuring an observable of a quantum system. As it can only be tested by measuring many copies of the system under consid…
on Oct 3
From quantum-journal.org
Topological photon pumping in quantum optical systems
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Mathias B. M. Svendsen, Marcel Cech, Max Schemmer, and Beatriz Olmos, Quantum 8, 1488 (2024). We establish the concept of topological pumping in one-dimensional systems with long-range couplings and apply it to the transport of a photon in quantum optical systems. In our theoretical…
on Oct 2
From quantum-journal.org
(Almost-)Quantum Bell Inequalities and Device-Independent Applications
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Yuan Liu, Ho Yiu Chung, and Ravishankar Ramanathan, Quantum 8, 1489 (2024). Investigations of the boundary of the quantum correlation set have gained increased attention in recent years. This is done through the derivation of quantum Bell inequalities, which are rel…
on Oct 2
From quantum-journal.org
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Zhiyan Ding, Haoya Li, Lin Lin, HongKang Ni, Lexing Ying, and Ruizhe Zhang, Quantum 8, 1487 (2024). Quantum phase estimation is one of the most powerful quantum primitives. This work proposes a new approach for the problem of multiple eigenvalue estimation: Quantum Multiple Eigenvalue Gaus…
on Oct 2
From quantum-journal.org
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Joshua Eglinton, Federico Carollo, Igor Lesanovsky, and Kay Brandner, Quantum 8, 1486 (2024). Microscopic thermal machines promise to play an important role in future quantum technologies. Making such devices widely applicable will require effective strategies to channel their output…
on Sep 26
From quantum-journal.org
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Yìlè Yīng, Marina Maciel Ansanelli, Andrea Di Biagio, Elie Wolfe, David Schmid, and Eric Gama Cavalcanti, Quantum 8, 1485 (2024). Nonclassical causal modeling was developed in order to explain violations of Bell inequalities while adhering to relativistic causal structure and...
on Sep 26
From quantum-journal.org
Adaptive Phase Estimation with Squeezed Vacuum Approaching the Quantum Limit
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M. A. Rodríguez-García and F. E. Becerra, Quantum 8, 1480 (2024). Phase estimation plays a central role in communications, sensing, and information processing. Quantum correlated states, such as squeezed states, enable phase estimation beyond the shot-nois…
on Sep 25
From quantum-journal.org
Wigner’s friend’s memory and the no-signaling principle
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Veronika Baumann and Časlav Brukner, Quantum 8, 1481 (2024). The Wigner's friend experiment is a thought experiment in which a so-called superobserver (Wigner) observes another observer (the friend) who has performed a quantum measurement on a physica…
on Sep 25
From quantum-journal.org
Tight and Efficient Gradient Bounds for Parameterized Quantum Circuits
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Alistair Letcher, Stefan Woerner, and Christa Zoufal, Quantum 8, 1484 (2024). The training of a parameterized model largely depends on the landscape of the underlying loss function. In particular, vanishing gradients are a central bottleneck in the scalability of vari…
on Sep 25
From quantum-journal.org
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Tan Van Vu, Tomotaka Kuwahara, and Keiji Saito, Quantum 8, 1483 (2024). Understanding the ultimate rate at which information propagates is a pivotal issue in nonequilibrium physics. Nevertheless, the task of elucidating the propagation speed inherent in quantum…
on Sep 25
From quantum-journal.org
Mitigating controller noise in quantum gates using optimal control theory
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Aviv Aroch, Ronnie Kosloff, and Shimshon Kallush, Quantum 8, 1482 (2024). All quantum systems are subject to noise from the environment or external controls. This noise is a major obstacle to the realization of quantum technology. For example, noise limits the fid…
on Sep 25
From quantum-journal.org
Efficient validation of Boson Sampling from binned photon-number distributions
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Benoit Seron, Leonardo Novo, Alex Arkhipov, and Nicolas J. Cerf, Quantum 8, 1479 (2024). In order to substantiate claims of quantum computational advantage, it is crucial to develop efficient methods for validating the experimental data. We propose a test of the correct function…
on Sep 19
From quantum-journal.org
Safeguarding Oscillators and Qudits with Distributed Two-Mode Squeezing
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Anthony J. Brady, Jing Wu, and Quntao Zhuang, Quantum 8, 1478 (2024). Recent advancements in multi-mode Gottesman-Kitaev-Preskill (GKP) codes have shown great promise in enhancing the protection of both discrete and analog quantum information. This broadened r…
on Sep 19
From quantum-journal.org
Sampling Error Analysis in Quantum Krylov Subspace Diagonalization
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Gwonhak Lee, Dongkeun Lee, and Joonsuk Huh, Quantum 8, 1477 (2024). Quantum Krylov subspace diagonalization (QKSD) is an emerging method used in place of quantum phase estimation in the early fault-tolerant era, where limited quantum circuit depth is availab…
on Sep 19
From quantum-journal.org
Efficient entanglement purification based on noise guessing decoding
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André Roque, Diogo Cruz, Francisco A. Monteiro, and Bruno C. Coutinho, Quantum 8, 1476 (2024). In this paper, we propose a novel bipartite entanglement purification protocol built upon hashing and upon the guessing random additive noise decoding (GRAND) approach recently devised for c…
on Sep 19
From quantum-journal.org
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Dawid A. Hryniuk and Marzena H. Szymańska, Quantum 8, 1475 (2024). We introduce a novel method of efficiently simulating the non-equilibrium steady state of large many-body open quantum systems with highly non-local interactions, based on a variational Mont…
on Sep 17