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We establish a method of directly measuring and estimating non-classicality - operationally defined in terms of the distinguishability of a given state from one with a positive Wigner function. It allows to certify non-classicality, based…

Quantum Physics · Physics 2011-05-03 A. Mari , K. Kieling , B. Melholt Nielsen , E. S. Polzik , J. Eisert

We show that quantum states with "low stabilizer complexity" can be efficiently distinguished from Haar-random. Specifically, given an $n$-qubit pure state $|\psi\rangle$, we give an efficient algorithm that distinguishes whether…

Quantum Physics · Physics 2025-09-18 Sabee Grewal , Vishnu Iyer , William Kretschmer , Daniel Liang

We introduce a quantifier of phase-space complexity for discrete-variable (DV) quantum systems. Motivated by a recent framework developed for continuous-variable systems, we construct a complexity measure of quantum states based on the…

Quantum Physics · Physics 2026-03-05 Siting Tang , Shunlong Luo , Matteo G. A. Paris

We derive exceedingly simple practical procedures revealing the quantum nature of states and measurements by the violation of classical upper bounds on the statistics of arbitrary measurements. Data analysis is minimum and definite…

Quantum Physics · Physics 2009-04-28 Ángel Rivas , Alfredo Luis

A test of quantumness is a protocol that allows a classical verifier to certify (only) that a prover is not classical. We show that tests of quantumness that follow a certain template, which captures recent proposals such as (Kalai et al.,…

In this work we generalize the Bochner criterion addressing the characteristic function, i.e., the Fourier transform, of the Glauber-Sudarshan phase-space function. For this purpose we extend the Bochner theorem by including derivatives of…

Quantum Physics · Physics 2015-07-29 Sergej Ryl , Jan Sperling , Elizabeth Agudelo , Melanie Mraz , Semjon Köhnke , Boris Hage , Werner Vogel

One of the most widespread methods to determine if a quantum state is entangled, or to quantify its entanglement dimensionality, is by measuring its fidelity with respect to a pure state. In this Letter we find a large class of states whose…

Quantum Physics · Physics 2020-08-14 Mirjam Weilenmann , Benjamin Dive , David Trillo , Edgar A. Aguilar , Miguel Navascués

General semiclassical expression for quantum fidelity (Loschmidt echo) of arbitrary pure and mixed states is derived. It expresses fidelity as an interference sum of dephasing trajectories weighed by the Wigner function of the initial…

Quantum Physics · Physics 2007-05-23 Jiri Vanicek

This paper explores the quantum detection of Phase-Shift Keying (PSK)-coded coherent states through the lens of active hypothesis testing, focusing on a Dolinar-like receiver with constraints on displacement amplitude and energy. With…

Quantum Physics · Physics 2025-01-28 Yun-Feng Lo , Matthieu R. Bloch

In the realm of fault-tolerant quantum computing, stabilizer operations play a pivotal role, characterized by their remarkable efficiency in classical simulation. This efficiency sets them apart from non-stabilizer operations within the…

Quantum Physics · Physics 2024-07-30 Chengkai Zhu , Zhiping Liu , Chenghong Zhu , Xin Wang

When increasing the dimensionality of quantum systems, high-dimensional quantum state certification becomes important in quantum information science and technology. However, how to certify ensembles of high-dimensional quantum states in a…

Quantum Physics · Physics 2026-02-20 Yong-Nan Sun , Meng-Yun Ma , Qi-Ping Su , Zhe Sun , Chui-Ping Yang , Franco Nori

Entangled quantum states, such as N00N states, are of major importance for quantum technologies due to their quantum-enhanced performance. At the same time, their quantum correlations are relatively vulnerable when they are subjected to…

Quantum Physics · Physics 2017-07-19 Martin Bohmann , Jan Sperling , Werner Vogel

The conventional certification method for quantum teleportation protocols relies on surpassing the highest achievable classical average fidelity between target and teleported states. Our investigation highlights the limitations of this…

Quantum Physics · Physics 2025-06-06 D. G. Bussandri , G. M. Bosyk , F. Toscano

We introduce a simple and efficient technique to verify quantum discord in unknown Gaussian states and a certain class of non-Gaussian states. We show that any separation in the peaks of the marginal distributions of one subsystem…

A three level atom in $\Lambda$ configuration is reduced to an effective two level system, under appropriate conditions, and its $\mathcal{PT}$ symmetric properties are investigated. This effective qubit system when subjected to a…

Quantum Physics · Physics 2022-06-10 Javid Naikoo , Subhashish Banerjee , Anirban Pathak

Gaussian states have played on important role in the physics of continuous-variable quantum systems. They are appealing for the experimental ease with which they can be produced, and for their compact and elegant mathematical description.…

Quantum Physics · Physics 2021-10-04 Mattia Walschaers

Symmetry is a unifying concept in physics. In quantum information and beyond, it is known that quantum states possessing symmetry are not useful for certain information-processing tasks. For example, states that commute with a Hamiltonian…

Quantum Physics · Physics 2023-09-27 Margarite L. LaBorde , Soorya Rethinasamy , Mark M. Wilde

The rapid advancement of quantum hardware calls for the development of reliable methods to certify its correct functioning. However, existing certification tests often fall short: they either rely on flawless state preparation and…

Quantum Physics · Physics 2026-03-16 Jan Nöller , Nikolai Miklin , Martin Kliesch , Mariami Gachechiladze

The task of testing whether two uncharacterized quantum devices behave in the same way is crucial for benchmarking near-term quantum computers and quantum simulators, but has so far remained open for continuous-variable quantum systems. In…

Quantum Physics · Physics 2023-05-29 Ya-Dong Wu , Yan Zhu , Ge Bai , Yuexuan Wang , Giulio Chiribella

Entanglement plays an indispensable role in numerous quantum information and quantum computation tasks, underscoring the need for efficiently verifying entangled states. In recent years, quantum state verification has received increasing…

Quantum Physics · Physics 2025-12-15 Lan Zhang , Yinfei Li , Ye-Chao Liu , Jiangwei Shang