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The standard quantum error correction protocols use projective measurements to extract the error syndromes from the encoded states. We consider the more general scenario of weak measurements, where only partial information about the error…

Quantum Physics · Physics 2019-01-31 Parveen Kumar , Apoorva Patel

It is shown how the evidence state space in quantum bit commitment may be made to depend on the bit value 0 or 1 with split entangled pairs. As a consequence, one can obtain a protocol that is perfectly concealing, but is also…

Quantum Physics · Physics 2007-05-23 Horace P. Yuen

We present a quasipolynomial-time algorithm for solving the weak membership problem for the convex set of separable, i.e. non-entangled, bipartite density matrices. The algorithm decides whether a density matrix is separable or whether it…

Quantum Physics · Physics 2011-06-13 Fernando G. S. L. Brandao , Matthias Christandl , Jon Yard

We investigate the structure of quantum proof systems by establishing collapse results that reveal simplifications in their complexity landscape. By extending classical theorems such as the Karp-Lipton theorem to quantum settings and…

Quantum Physics · Physics 2025-07-08 Kartik Anand , Kabgyun Jeong , Junseo Lee

A method is presented for achieving entanglement-free teleportation of a quantum state subject to any quantum noise. We apply this as a light-speed noise-resistant communicator, but also treat the possibility of a quantum ansible, a device…

General Physics · Physics 2016-05-31 Samuel R. Hedemann

In this paper we explore the possibility of performing Heisenberg limited quantum metrology of a phase, without any prior, by employing only maximally entangled states. Starting from the estimator introduced by Higgins et al. in New J.…

Quantum Physics · Physics 2020-10-27 Federico Belliardo , Vittorio Giovannetti

By using local quantum teleportation of a fixed state to one qubit of an entangled pair sent from the other party, it is shown how one party can commit a bit with only classical information as evidence that results in an unconditionally…

Quantum Physics · Physics 2007-05-23 Horace P. Yuen

Private comparison is a primitive for many cryptographic tasks, and recently several schemes for the quantum private comparison (QPC) have been proposed, where two users can compare the equality of their secrets with the help of a…

Quantum Physics · Physics 2022-06-07 Kishore Thapliyal , Rishi Dutt Sharma , Anirban Pathak

Suppose that a polynomial-time mixed-state quantum circuit, described as a sequence of local unitary interactions followed by a partial trace, generates a quantum state shared between two parties. One might then wonder, does this quantum…

Quantum Physics · Physics 2016-11-17 Patrick Hayden , Kevin Milner , Mark M. Wilde

We propose a simple protocol for the verification of quantum computation after the computation has been performed. Our construction can be seen as an improvement on previous results in that it requires only a single prover, who is…

Quantum Physics · Physics 2018-03-19 Tomoyuki Morimae , Joseph F. Fitzsimons

We consider quantum MDS (QMDS) codes for quantum systems of dimension $q$ with lengths up to $q^2+2$ and minimum distances up to $q+1$. We show how starting from QMDS codes of length $q^2+1$ based on cyclic and constacyclic codes, new QMDS…

Quantum Physics · Physics 2016-01-25 Markus Grassl , Martin Roetteler

In this article we study the role that quantum resources play in quantum error correction assisted quantum metrology (QECQM) schemes. We show that there exist classes of such problems where entanglement is not necessary to retrieve noise…

Quantum Physics · Physics 2019-08-21 K. C. Tan , S. Omkar , H. Jeong

Two orthogonal-state-based protocols of quantum key agreement (QKA) are proposed. The first protocol of QKA proposed here is designed for two-party QKA, whereas the second protocol is designed for multi-party QKA. Security of these…

Quantum Physics · Physics 2014-07-09 Chitra Shukla , Nasir Alam , Anirban Pathak

We significantly extend recently developed methods to faithfully reconstruct unknown quantum states that are approximately low-rank, using only a few measurement settings. Our new method is general enough to allow for measurements from a…

Quantum Physics · Physics 2012-07-11 Matthias Ohliger , Vincent Nesme , David Gross , Yi-Kai Liu , Jens Eisert

Self-testing of quantum devices based on observed measurement statistics is a method to certify quantum systems using minimal resources. In Ref. [Phys. Rev. \textbf{A} 101, 032106 (2020)], a scheme based on observing measurement statistics…

Quantum Physics · Physics 2024-12-03 Chellasamy Jebarathinam , Gautam Sharma , Sk Sazim , Remigiusz Augusiak

Protocols for quantum measurement are an essential part of quantum computing. Measurements are no longer confined to the final step of computation but are increasingly embedded within quantum circuits as integral components of…

Quantum Physics · Physics 2025-11-07 Michal Krejčí , Lucie Krejčí , Ijaz Ahamed Mohammad , Martin Plesch , Martin Friák

We propose a scheme for optimal Gaussian purification of coherent states from several imperfect copies. The proposal is experimentally demonstrated for the case of two copies of a coherent state sent through independent noisy channels. Our…

Quantum Physics · Physics 2009-11-11 Ulrik L. Andersen , Radim Filip , Jaromir Fiurasek , Vincent Josse , Gerd Leuchs

We study the use of entanglement purification for quantum communication over long distances. For distances much longer than the coherence length of a corresponding noisy quantum channel, the fidelity of transmission is usually so low that…

Quantum Physics · Physics 2008-12-18 W. Dür , H. - J. Briegel , J. I. Cirac , P. Zoller

The coherent-state qubit is a promising candidate for optical quantum information processing due to its nearly-deterministic nature of the Bell-state measurement (BSM). However, its non-orthogonality incurs difficulties such as failure of…

Quantum Physics · Physics 2021-12-23 Seok-Hyung Lee , Seung-Woo Lee , Hyunseok Jeong

Quantum repeaters are enabling technologies for long-distance quantum communications. Despite the significant progress in the field, we still not only face implementation challenges but also need theoretical solutions that better meet all…

Quantum Physics · Physics 2025-11-04 Javier Rey-Domínguez , Mohsen Razavi