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We investigate the use of discrete-time quantum walks to sample from an almost-uniform distribution, in the absence of any external source of randomness. Integers are encoded on the vertices of a cycle graph, and a quantum walker evolves…

Quantum Physics · Physics 2025-11-12 Marco Radaelli , Claudia Benedetti , Stefano Olivares

We study the properties of quasi-distributions or Wigner measures in the context of noncommutative quantum mechanics. In particular, we obtain necessary and sufficient conditions for a phase-space function to be a noncommutative Wigner…

Mathematical Physics · Physics 2014-11-20 C. Bastos , N. C. Dias , J. N. Prata

We propose a method for finding approximate compilations of quantum unitary transformations, based on techniques from policy gradient reinforcement learning. The choice of a stochastic policy allows us to rephrase the optimization problem…

Quantum Physics · Physics 2022-09-14 David A. Herrera-Martí

We present a scheme to estimate Gaussian states of one-dimensional continuous variable systems, based on weak (unsharp) quantum measurements. The estimation of a Gaussian state requires us to find position ($q$), momentum ($p$) and their…

Quantum Physics · Physics 2017-04-05 Debmalya Das , Arvind

We present a procedure for averaging one-parameter random unitary groups and random self-adjoint groups. Central to this is a generalization of the notion of weak convergence of a sequence of measures and the corresponding generalization of…

Mathematical Physics · Physics 2021-07-13 John E. Gough , Yurii N. Orlov , Vsevolod Zh. Sakbaev , Oleg G. Smolyanov

The current generation of quantum computing technologies call for quantum algorithms that require a limited number of qubits and quantum gates, and which are robust against errors. A suitable design approach are variational circuits where…

Quantum Physics · Physics 2020-04-10 Maria Schuld , Alex Bocharov , Krysta Svore , Nathan Wiebe

Weak measurements are a new tool for characterizing post-selected quantum systems during their evolution. Weak measurement was originally formulated in terms of von Neumann interactions which are practically available for only the simplest…

Quantum Physics · Physics 2009-11-11 J. S. Lundeen , K. J. Resch

Weak measurement is a new way to manipulate and control quantum systems. Different from projection measurement, weak measurement only makes a small change in status. Applying weak measurement to quantum discord, Singh and Pati proposed a…

Quantum Physics · Physics 2015-02-16 Tao Li , Teng Ma , Yaokun Wang , Shaoming Fei , Zhixi Wang

Graphical models are useful tools for describing structured high-dimensional probability distributions. Development of efficient algorithms for generating unbiased and independent samples from graphical models remains an active research…

Quantum Physics · Physics 2026-04-02 Nico Piatkowski , Christa Zoufal

A model is proposed for the statistical analysis of arbitrary-strength quantum measurements, based on a picture of "sampling weak values" from different configurations of the system. The model is comprised of two elements: a "local weak…

Quantum Physics · Physics 2007-05-23 Alonso Botero

We report the experimental measurement of bipartite quantum correlations of an unknown two-qubit state. Using a liquid state Nuclear Magnetic Resonance (NMR) setup and employing geometric discord, we evaluate the quantum correlations of a…

Ultracold atomic systems offer a unique tool for understanding behavior of matter in the quantum degenerate regime, promising studies of a vast range of phenomena covering many disciplines from condensed matter to quantum information and…

Quantum Physics · Physics 2016-08-16 Gabriel Mazzucchi , Santiago F. Caballero-Benitez , Igor B. Mekhov

Constructing an ontology for quantum theory is challenging, in part due to unavoidable measurement back-action. The Aharonov-Albert-Vaidman weak measurement formalism provides a method to predict measurement results (weak values) in a…

Quantum Physics · Physics 2019-09-04 Josiah Sinclair , David Spierings , Aharon Brodutch , Aephraim M. Steinberg

Weak measurement of a quantum system followed by postselection based on a subsequent strong measurement gives rise to a quantity called the weak value: a complex number for which the interpretation has long been debated. We analyse the…

Quantum Physics · Physics 2015-07-16 Angela Karanjai , Eric G. Cavalcanti , Stephen D. Bartlett , Terry Rudolph

In this article we introduce a quasiprobability distribution of work that is based on the Wigner function. This construction rests on the idea that the work done on an isolated system can be coherently measured by coupling the system to a…

Quantum Physics · Physics 2023-11-03 Federico Cerisola , Franco Mayo , Augusto J. Roncaglia

We introduce a general method for the construction of quasiprobability representations for arbitrary notions of quantum coherence. Our technique yields a nonnegative probability distribution for the decomposition of any classical state.…

Quantum Physics · Physics 2018-06-22 J. Sperling , I. A. Walmsley

The conventional method of qubit measurements in circuit QED is employing the dispersive regime of qubit-cavity coupling, which results in an approximated scheme of quantum nondemolition (QND) readout. This scheme becomes problematic in the…

Quantum Physics · Physics 2019-03-12 Wei Feng , Cheng Zhang , Zhong Wang , Lupei Qin , Xin-Qi Li

Quantum measurements and phase transitions are seemingly uncorrelated topics, but here we show that phase transitions occur in sequential quantum measurements. We find that the probability distribution of the measurement results of a…

Quantum Physics · Physics 2018-07-17 Wen-Long Ma , Ping Wang , Weng-Hang Leong , Ren-Bao Liu

A quantum state contains the maximal amount of information available for a given quantum system. In this paper we use weak-value expressions to reconstruct quantum states of continuous-variable systems in the quantum optical domain. The…

Quantum Physics · Physics 2012-11-15 Joachim Fischbach , Matthias Freyberger

Traditional uncertainty relations dictate a minimal amount of noise in incompatible projective quantum measurements. However, not all measurements are projective. Weak measurements are minimally invasive methods for obtaining partial state…

Quantum Physics · Physics 2021-03-15 Jonathan T. Monroe , Nicole Yunger Halpern , Taeho Lee , Kater W. Murch