Article
Quantum Science & Technology
Yoshifumi Nakata, Eyuri Wakakuwa, Masato Koashi
Summary: The paper extends the Hayden-Preskill protocol to study the effect of symmetry on information leakage. It is found that symmetry induces a delay in leakage and leaves behind an information remnant, which are related to the thermodynamic properties and symmetry-breaking of the system. This study bridges the information leakage problem with the macroscopic physics of quantum many-body systems.
Article
Physics, Multidisciplinary
Yuan Yuan, Xufeng Huang, Yueping Niu, Shangqing Gong
Summary: This paper analyzes the performance of estimating quantum coherence with Bell state measurement and finds that Bell state measurement is the optimal measurement for estimating several frequently-used coherence quantifiers.
Article
Quantum Science & Technology
Yanjun Chu, Fang Huang, Ming-Xiao Li, Zhu-Jun Zheng
Summary: Motivated by the isomorphic correspondence between quantum channels and their Choi states, this paper defines an entropy function of a quantum channel based on the entropy of its Choi state. The relation between entropy and relative entropy of a quantum channel is also discussed. Furthermore, the equivalence of two definitions of channel entropy is proved for covariant channels. Examples including the erasure channel, the d-dimensional depolarizing channel, and a specific type of Werner-Holevo channels are computed to illustrate the defined entropies.
QUANTUM INFORMATION PROCESSING
(2022)
Article
Physics, Multidisciplinary
Jerome Denis, Francois Damanet, John Martin
Summary: This study analyzes the accuracy of artificial neural networks (ANNs) in predicting the geometric measure of entanglement using a limited number of Wehrl moments as input. The results show that even powerful convergence acceleration algorithms cannot compete with ANNs given the same input data, as long as sufficient training data is available. Additionally, the study presents an experimental protocol for measuring Wehrl moments that is independent of the state.
Article
Physics, Multidisciplinary
G. Enzian, L. Freisem, J. J. Price, A. O. Svela, J. Clarke, B. Shajilal, J. Janousek, B. C. Buchler, P. K. Lam, M. R. Vanner
Summary: Quantum optical measurement techniques have been utilized to perform non-Gaussian mechanical state preparation and tomography of mechanical phase-space distribution, advancing the optics-based tomography of mechanical states to a new level.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Piotr Sierant, Xhek Turkeshi
Summary: In this study, we investigate the structure of many-body wave functions of 1D quantum circuits with local measurements using participation entropies. We find that the system size dependence of participation entropy shows a model-dependent multifractal scaling of the wave functions at any nonzero measurement rate. The subleading term of participation entropy contains universal information about measurement-induced phase transitions and acts as an order parameter, remaining constant and nonzero in the error-correcting phase and becoming zero in the quantum Zeno phase.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Hao-Sheng Zeng, Lian-Jie Wu
Summary: In this study, we investigate the combined effects of Unruh effect and Schwinger effect on quantum correlations. We find that both relativistic effects degrade the initial state's quantum correlations, which are then redistributed among the particles and antiparticles produced by these effects. The different behaviors exhibited by these effects and the conservation of quantum correlation in the process are examined.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Physics, Multidisciplinary
Francesco Buscemi, Joseph Schindler, Dominik Safranek
Summary: Observational entropy provides a general notion of quantum entropy that interpolates between Boltzmann's and Gibbs' entropies and is useful for measuring out-of-equilibrium thermodynamic entropy. This study focuses on the mathematical properties of observational entropy from an information-theoretic perspective, using strengthened monotonicity properties of quantum relative entropy. The concept of a 'coarse-grained' state, derived from measurement statistics through Bayesian retrodiction, plays a central role in this work and allows for upper and lower bounds on the difference between observational and von Neumann entropies.
NEW JOURNAL OF PHYSICS
(2023)
Article
Optics
F. Benatti, S. Olivares, G. Perosa, D. Bajoni, S. Di Mitri, R. Floreanini, L. Ratti, F. Parmigiani
Summary: The study proposes a method based on maximum likelihood techniques to reconstruct the energy state occupation number distribution of FEL radiation, addressing the photo-counting issues at high intensities. In addition to focusing on the statistical features of FEL radiation, the proposal is also applicable to the study of general nonlinear optical processes regarding the preservation of quantum features.
Article
Optics
Ralf Betzholz, Yu Liu, Jianming Cai
Summary: In this study, a method is proposed for the direct measurement of the Wigner characteristic function of a thermalizing harmonic oscillator, which is achieved through a probe-measurement-based scheme and extended to nonunitary time evolution. Analytical expressions are derived to account for decoherence during the measurement process.
Article
Physics, Multidisciplinary
Heng-Mei Li, Bao-Hua Yang, Hong-Chun Yuan, Ye-Jun Xu
Summary: A scheme is proposed to study the non-classical states generated by a quantum scissors device (QSD) operating on the cavity mode of an optomechanical system. The resulting state, obtained by the catalytic QSD acting on the cavity mode, consists of vacuum, single-photon, and two-photon states, depending on the coupling parameter and transmission coefficients. By selecting an appropriate coupling parameter, the output state becomes a class of multicomponent cat state truncations at time t = 2 pi. The research also investigates the success probability, fidelity, entanglement, and Wigner function of the system.
Article
Physics, Multidisciplinary
Ahana Chakraborty, Rajdeep Sensarma
Summary: This study introduces a new field theoretic method for calculating Renyi entropy of interacting bosons in subsystems without using replica methods. The method can be applied to dynamics of open and closed quantum systems, and can determine the relationship between the initial state and final density matrix to predict the behavior of entropy over time. The approach also shows that the entropy in non-Markovian dynamics approaches a steady-state value with exponents determined by nonanalyticities of the system's environment.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Marcelo Losada, Victor A. Penas, Federico Holik, Pedro W. Lamberti
Summary: In this study, we investigate the reduced density matrices of sublattices in fermionic, bosonic, and spin lattice models. For fermionic and bosonic lattice models, it is found that the reduced density matrix associated with a sublattice coincides with the state obtained by applying the maximum entropy principle under suitably chosen constraints. In the case of informationally incomplete scenarios, spin lattice models are considered, and the performance of the MaxEnt method for estimating the reduced density matrix of sublattices is studied. It is found that the performance of the MaxEnt estimation improves not only with the number of measured observables but also with the lattice length.
PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS
(2022)
Article
Astronomy & Astrophysics
Kanato Goto, Tomoki Nosaka, Masahiro Nozaki
Summary: The magic property of quantum states is important for achieving universal quantum computation and is related to the chaotic and integrable nature of the system. The study finds that in the chaotic regime, magic increases with time and eventually stabilizes, while in the integrable regime, magic shows periodic behavior. These results suggest a strong connection between the magic of quantum states and the emergence of spacetime geometry.
Article
Optics
Murillo R. Silva, Alexys Bruno-Alfonso
Summary: This study retrieves the exact phase of one-dimensional quantum states with given Gaussian probability densities in the position and momentum representations, with the number of Pauli partners found depending on the saturation of the Heisenberg uncertainty relation. Without saturation, two Pauli partners are found, differing in the sign of the time derivative of their position uncertainties. The same problem is solved using an exact implementation of the Gerchberg-Saxton algorithm, with its convergence also depending on uncertainty saturation.
Article
Physics, Multidisciplinary
Yong Siah Teo, Kimin Park, Seongwook Shin, Hyunseok Jeong, Petr Marek
Summary: A practical strategy for selecting near-optimal sets of input coherent states for reconstructing single-mode Gaussian quantum processes is proposed. By relaxing the trace-preserving constraint, an error-reducing set of input coherent states independent of measurement data or the unknown true process is introduced. Numerical experiments show that the process reconstruction from these input coherent states is nearly as accurate as using the best possible set of coherent states chosen with complete knowledge about the process.
NEW JOURNAL OF PHYSICS
(2021)
Article
Computer Science, Theory & Methods
Yong Siah Teo, Luis L. Sanchez-Soto
Summary: This review provides a concise introductory survey of modern compressive tomography developed since 2019, focusing on characterizing arbitrary low-rank quantum objects using minimal measuring resources without prior assumptions. The paper contains technical details for the quantum-information community to apply the discussed methods, presented in a pedagogical manner to facilitate understanding of the formulation logic and physics of compressive tomography.
INTERNATIONAL JOURNAL OF QUANTUM INFORMATION
(2021)
Article
Physics, Multidisciplinary
Yong Siah Teo, Seongwook Shin, Hyunseok Jeong, Yosep Kim, Yoon-Ho Kim, Gleb Struchalin, Egor Kovlakov, Stanislav S. Straupe, Sergei P. Kulik, Gerd Leuchs, Luis L. Sanchez-Soto
Summary: In this study, convolutional neural networks are trained to predict the completeness of information in quantum measurements, accelerating the characterization of quantum states. Experimental results show that trained networks can significantly reduce certification time and improve the computation yield of large-scale quantum processors.
NEW JOURNAL OF PHYSICS
(2021)
Article
Optics
Jano Gil-Lopez, Yong Siah Teo, Syamsundar De, Benjamin Brecht, Hyunseok Jeong, Christine Silberhorn, Luis L. Sanchez-Soto
Summary: In this study, an adaptive compressive tomography scheme is implemented to reconstruct any arbitrary low-rank spectral-temporal optical signal with extremely few measurement settings. The method showcases versatility and introduces a universal optical reconstruction framework to these platforms through conclusive experimental results for both temporal modes and frequency bins.
Article
Chemistry, Physical
Jerzy Cioslowski, Berthold-Georg Englert, Martin-Isbjoern Trappe, Jun Hao Hue
Summary: At the limit of infinite confinement strength, the ground state of a system containing two interacting fermions or bosons in harmonic confinement remains strongly correlated. The natural orbitals of this system exhibit peculiar properties, such as nonzero collective occupancies for all angular momenta and a relationship with eigenfunctions and eigenvalues of a zero-energy Schrodinger equation with an attractive Gaussian potential. These properties have implications for the decay behavior and energy contributions of the system.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Quantum Science & Technology
Seok-Hyung Lee, Srikrishna Omkar, Yong Siah Teo, Hyunseok Jeong
Summary: Measurement-based quantum computing (MBQC) in linear optical systems is a promising approach for achieving quantum computing in the near future. This work proposes a linear optical topological MBQC protocol using multiphoton qubits based on parity encoding, which is highly tolerant to photon losses and efficient in terms of resources. A Bayesian methodology and stabilizer formalism are introduced for realistic error analysis, and a graph-theoretical optimization scheme is suggested for constructing arbitrary graph states with reduced resource overhead. The protocol is shown to outperform existing approaches in terms of fault-tolerance and resource usage.
NPJ QUANTUM INFORMATION
(2023)
Article
Optics
S. Shin, Y. S. Teo, H. Jeong
Summary: The expressivity of quantum circuits and measurement resources is crucial for reliable quantum supervised learning. This study introduces hardware-efficient exponential-data-encoding strategies that outperform all nonentangling Pauli-encoded schemes, allowing quantum circuits to express general functions with wide Fourier frequency spectra using exponentially fewer encoding gates. The results show that such encoding strategies not only reduce quantum resources but also demonstrate practical advantages during training compared to known efficient classical strategies, especially when polynomial-depth training circuits are employed. Numerical simulations suggest that even exponential-data-encoding circuits with single-layer training modules can generally express functions outside the classically expressible region, providing practical benefits of this resource advantage. Finally, the performance of exponential encoding in learning the potential-energy surface of the ethanol molecule and California's housing prices is illustrated.
Article
Optics
Y. S. Teo
Summary: This paper discusses the importance of sampling noisy intermediate-scale quantum devices, introduces numerical estimators, and proposes optimized methods based on operational circuit-averaged approaches to minimize estimation errors. The experiments show that these optimized numerical estimators offer exponentially decreasing estimation errors with an increasing number of circuit qubits, and are compatible with the barren-plateau phenomenon. Additionally, an optimized difference estimator provides a smaller average estimation error compared to the standard parameter-shift estimator below a critical sampling-copy number, which grows exponentially with the circuit-qubit number. Finally, by forsaking analyticity, it is demonstrated that scaled parameter-shift estimators outperform unscaled estimators in estimation accuracy under any situation, with comparable performances to difference estimators within significant copy-number ranges, and are the best choice if larger copy numbers are affordable.
Article
Optics
Yong Siah Teo, Seongwook Shin, Hyukgun Kwon, Seok-Hyung Lee, Hyunseok Jeong
Summary: Virtual distillation is an error-mitigation technique that reduces quantum-computation errors without assuming the noise type. The performance of error mitigation can be improved by uniformly distributing peripherals across the entire quantum circuit.
Article
Quantum Science & Technology
Srikrishna Omkar, Seok-Hyung Lee, Yong Siah Teo, Seung-Woo Lee, Hyunseok Jeong
Summary: This article proposes an architecture for linear-optical quantum computing based on three-photon GHZ states. By combining topological quantum error-correction codes with three-qubit repetition codes, the architecture can tolerate a remarkably high photon-loss rate. Compared to other schemes, this architecture is resource efficient and can be further improved if larger GHZ states are available. The article suggests that this scheme brings scalable photonic quantum computing a step closer to reality, with its significant enhancement in the photon-loss threshold and recent progress in generating multiphoton entanglement.
Article
Optics
Dominik Koutny, Libor Motka, Zdenek Hradil, Jaroslav Rehacek, Luis L. Sanchez-Soto
Summary: Researchers revisit the application of neural networks to quantum state tomography and confirm that the positivity constraint can be successfully implemented through training. Their findings suggest that this approach can be used for quantum state reconstruction under various types of noise.
Article
Optics
A. Mikhalychev, Y. S. Teo, H. Jeong, A. Stefanov, D. Mogilevtsev
Summary: The study proposes a method to emulate quantum phenomena using a finite set of mixtures of coherent states. This allows for easier generation in the laboratory and successful reproduction of well-known quantum effects.
Proceedings Paper
Computer Science, Information Systems
A. Mikhalychev, Y. S. Teo, H. Jeong, A. Stefanov, D. Mogilevtsev
Summary: This study introduces a classical emulation methodology to emulate quantum phenomena using a finite set of coherent states, shedding new light on an alternative operational meaning to non-classicality. It demonstrates the capabilities in observing the Hong-Ou-Mandel effect, violating Bell inequalities, and witnessing quantum non-classicality.
2021 IEEE INTERNATIONAL CONFERENCE ON MICROWAVES, ANTENNAS, COMMUNICATIONS AND ELECTRONIC SYSTEMS (COMCAS)
(2021)
Article
Optics
S. Omkar, Y. S. Teo, Seung-Woo Lee, H. Jeong
Summary: We investigate a scheme for topological quantum computing using optical hybrid qubits and show an improved photon loss threshold. By creating a special cluster state, known as Raussendorf lattice, the threshold is enhanced up to 5.7 x 10(-3). Although this improvement comes with increased resource consumption compared to previous schemes, it remains more resource-efficient compared to other known optical schemes for fault-tolerant quantum computation.
