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We define a new family of codes for symmetric classical-quantum channels and establish their optimality. To this end, we extend the classical notion of generalized perfect and quasi-perfect codes to channels defined over some finite…

Quantum Physics · Physics 2020-07-17 Andreu Blasco Coll , Gonzalo Vazquez-Vilar , Javier R. Fonollosa

We study approximation of embeddings between finite dimensional L_p spaces in the quantum model of computation. For the quantum query complexity of this problem matching (up to logarithmic factors) upper and lower bounds are obtained. The…

Quantum Physics · Physics 2007-05-23 Stefan Heinrich

Quantum error correction (QEC) is an essential concept for any quantum information processing device. Typically, QEC is designed with minimal assumptions about the noise process; this generic assumption exacts a high cost in efficiency and…

Quantum Physics · Physics 2007-06-26 Andrew S. Fletcher

We consider semidefinite programming (SDP) for the binary stochastic block model with equal-sized communities. Prior work of Hajek, Wu, and Xu proposed an SDP (sym-SDP) for the symmetric case where the intra-community edge probabilities are…

Information Theory · Computer Science 2025-06-24 Julia Gaudio , Phawin Prongpaophan

In recent years, parameterized quantum circuits have become a major tool to design quantum algorithms for optimization problems. The challenge in fully taking advantage of a given family of parameterized circuits lies in finding a good set…

Quantum Physics · Physics 2022-09-05 Eunou Lee

This paper develops a new storage-optimal algorithm that provably solves generic semidefinite programs (SDPs) in standard form. This method is particularly effective for weakly constrained SDPs. The key idea is to formulate an approximate…

Optimization and Control · Mathematics 2020-06-19 Lijun Ding , Alp Yurtsever , Volkan Cevher , Joel A. Tropp , Madeleine Udell

The highest information rate at which quantum error-correction schemes work reliably on a channel, which is called the quantum capacity, is proven to be lower bounded by the limit of the quantity termed coherent information maximized over…

Quantum Physics · Physics 2007-05-23 Mitsuru Hamada

We study optimization programs given by a bilinear form over non-commutative variables subject to linear inequalities. Problems of this form include the entangled value of two-prover games, entanglement-assisted coding for classical…

Quantum Physics · Physics 2016-08-15 Mario Berta , Omar Fawzi , Volkher B. Scholz

This paper introduces a method for calculating the quantum relative entropy of channels, an essential quantity in quantum channel discrimination and resource theories of quantum channels. By building on recent developments in the…

Quantum Physics · Physics 2026-04-16 Gereon Koßmann , Mark M. Wilde

Basing on states and channels isomorphism we point out that semidefinite programming can be used as a quick test for nonzero one-way quantum channel capacity. This can be achieved by search of symmetric extensions of states isomorphic to a…

Quantum Physics · Physics 2015-06-26 Pawel Horodecki , Marcin L. Nowakowski

The fidelity function of quantum states have been widely used in quantum information science and frequently arises in the quantification of optimal performances for the estimation and distinguish of quantum states. A fidelity function on…

Quantum Physics · Physics 2017-03-09 Haidong Yuan , Chi-Hang Fred Fung

Solving optimization problems is a key task for which quantum computers could possibly provide a speedup over the best known classical algorithms. Particular classes of optimization problems including semi-definite programming (SDP) and…

In this work we aim at quantifying quantum channel output similarity. In order to achieve this, we introduce the notion of quantum channel superfidelity, which gives us an upper bound on the quantum channel fidelity. This quantity is…

Quantum Physics · Physics 2018-10-12 Łukasz Pawela , Zbigniew Puchała

We study distributed similarity estimation of quantum channels (DSEC), a primitive for cross-platform verification where two remote quantum devices are compared by estimating the inner product of their Choi states. We show that the optimal…

Quantum Physics · Physics 2026-01-19 Congcong Zheng , Kun Wang , Xutao Yu , Ping Xu , Zaichen Zhang

A fundamental problem in quantum coding theory is to determine the maximum size of quantum codes of given block length and distance. A recent work introduced bounds based on semidefinite programming, strengthening the well-known quantum…

Quantum Physics · Physics 2026-03-23 Gerard Anglès Munné , Felix Huber

To establish an entangled state of optimal fidelity between two distant observers when the available quantum channel is noisy, is a central problem in quantum information theory. We consider an instance of this problem for two-qubit systems…

Quantum Physics · Physics 2012-09-18 Somshubhro Bandyopadhyay , Anindita Ghosh

Quantum key distribution (QKD) allows for secure communications safe against attacks by quantum computers. QKD protocols are performed by sending a sizeable, but finite, number of quantum signals between the distant parties involved. Many…

Quantum Physics · Physics 2021-01-05 Darius Bunandar , Luke C. G. Govia , Hari Krovi , Dirk R. Englund

Understanding and approximating extremal energy states of local Hamiltonians is a central problem in quantum physics and complexity theory. Recent work has focused on developing approximation algorithms for local Hamiltonians, and in…

Quantum Physics · Physics 2026-04-10 Jun Takahashi , Chaithanya Rayudu , Cunlu Zhou , Robbie King , Kevin Thompson , Ojas Parekh

Semidefinite programs (SDPs) are convex optimization programs with vast applications in control theory, quantum information, combinatorial optimization and operational research. Noisy intermediate-scale quantum (NISQ) algorithms aim to make…

Quantum Physics · Physics 2023-01-31 Kishor Bharti , Tobias Haug , Vlatko Vedral , Leong-Chuan Kwek

In recent years there has been growing interest in study of multi-antenna transmit designs for providing secure communication over the physical layer. This paper considers the scenario of an intended multi-input single-output channel…

Information Theory · Computer Science 2015-05-20 Qiang Li , Wing-Kin Ma