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We consider the notion of unitary transformations forming bases for subspaces of $M(d,\mathbb{C})$ such that the square of Hilbert-Schmidt inner product of matrices from the differing bases is a constant. Moving from the qubit case,…

Quantum Physics · Physics 2016-11-24 Jesni Shamsul Shaari , Rinie N. M. Nasir , Stefano Mancini

Quantum computers are analog devices; thus they are highly susceptible to accumulative errors arising from classical control electronics. Fast operation--as necessitated by decoherence--makes gating errors very likely. In most current…

Quantum Physics · Physics 2009-11-07 Mark Friesen , Robert Joynt , M. A. Eriksson

Quantum homomorphic encryption, which allows computation by a server directly on encrypted data, is a fundamental primitive out of which more complex quantum cryptography protocols can be built. For such constructions to be possible,…

Quantum Physics · Physics 2023-04-19 Yanglin Hu , Yingkai Ouyang , Marco Tomamichel

We obtain the strongest separation between quantum and classical query complexity known to date -- specifically, we define a black-box problem that requires exponentially many queries in the classical bounded-error case, but can be solved…

Quantum Physics · Physics 2007-05-23 J. Niel de Beaudrap , Richard Cleve , John Watrous

A general class of authentication schemes for arbitrary quantum messages is proposed. The class is based on the use of sets of unitary quantum operations in both transmission and reception, and on appending a quantum tag to the quantum…

Quantum Physics · Physics 2015-06-26 Esther Perez , Marcos Curty , David J. Santos , Priscila Garcia-Fernandez

Quantum-mechanical devices have the potential to transform cryptography. Most research in this area has focused either on the information-theoretic advantages of quantum protocols or on the security of classical cryptographic schemes…

Semi-quantum secret sharing (SQSS) is an important branch of semi-quantum cryptography, and differs from quantum secret sharing (QSS) in that not all parties are required to possess quantum capabilities. All previous SQSS protocols have…

Quantum Physics · Physics 2022-05-18 Chong-Qiang Ye , Tian-Yu Ye

The Swap gate is a ubiquitous tool for moving information on quantum hardware, yet it can be considered a classical operation because it does not entangle product states. Genuinely quantum operations could outperform Swap for the task of…

Quantum Physics · Physics 2023-02-02 Aniruddha Bapat , Andrew M. Childs , Alexey V. Gorshkov , Eddie Schoute

A random access code (RAC) is a strategy to encode a message into a shorter one in a way that any bit of the original can still be recovered with nontrivial probability. Encoding with quantum bits rather than classical ones can improve this…

Quantum Physics · Physics 2020-08-21 Giulio Foletto , Luca Calderaro , Giuseppe Vallone , Paolo Villoresi

Post-quantum cryptography studies the security of classical, i.e. non-quantum cryptographic protocols against quantum attacks. Until recently, the considered adversaries were assumed to use quantum computers and behave like classical…

Cryptography and Security · Computer Science 2013-07-16 Maria Velema

Processing qubit Hamiltonians derived from electronic-structure problems can become classically prohibitive because many downstream manipulations still rely on dense operator constructions whose cost grows exponentially with qubit number.…

Quantum Physics · Physics 2026-03-10 Yuqi Zhang , Sixu Chen , Feixiong Cheng , Qiang Guan

Random circuit sampling (RCS) is a leading approach to demonstrate quantum advantage, with its believed classical hardness rooted in anticoncentration of output distributions and average-case hardness of probability estimation. Here we show…

Quantum Physics · Physics 2026-04-16 Bingzhi Zhang , Quntao Zhuang

This paper introduces a novel lower bound on communication complexity using quantum relative entropy and mutual information, refining previous classical entropy-based results. By leveraging Uhlmann's lemma and quantum Pinsker inequalities,…

Quantum Physics · Physics 2025-07-29 Fengxia Liu , Zhiyong Zheng , Kun Tian , Yi Zhang , Heng Guo , Zhe Hu , Oleksiy Zhedanov , Zixian Gong

Near-term quantum machine learning must balance expressivity, optimization, and hardware constraints. We study quantum re-uploading units (QRUs) as compact circuits and compare them, at matched parameter count, to a standard mono-encoded…

Quantum Physics · Physics 2026-02-03 Léa Cassé , Bernhard Pfahringer , Albert Bifet , Frédéric Magniette

Biomarker-based prediction of clinical outcomes is challenging due to nonlinear relationships, correlated features, and the limited size of many medical datasets. Classical machine-learning methods can struggle under these conditions,…

We prove that it is impossible to construct perfect-complete quantum public-key encryption (QPKE) with classical keys from quantumly secure one-way functions (OWFs) in a black-box manner, resolving a long-standing open question in quantum…

Quantum Physics · Physics 2025-04-09 Longcheng Li , Qian Li , Xingjian Li , Qipeng Liu

Quantum resources and protocols are known to outperform their classical counterparts in variety of communication and information processing tasks. Random Access Codes (RACs) are one such cryptographically significant family of bipartite…

Quantum Physics · Physics 2021-07-28 Vaisakh M , Ram krishna Patra , Mukta Janpandit , Samrat Sen , Anubhav Chaturvedi , Manik Banik

Quantum entanglement, perhaps the most non-classical manifestation of quantum information theory, cannot be used to transmit information between remote parties. Yet, it can be used to reduce the amount of communication required to process a…

Quantum Physics · Physics 2015-06-29 Gilles Brassard , Anne Broadbent , Alain Tapp

We prove a quantum information-theoretic conjecture due to Ji, Liu and Song (CRYPTO 2018) which suggested that a uniform superposition with random \emph{binary} phase is statistically indistinguishable from a Haar random state. That is, any…

Quantum Physics · Physics 2019-06-27 Zvika Brakerski , Omri Shmueli

It has been observed that particular rate-1/2 partially systematic parallel concatenated convolutional codes (PCCCs) can achieve a lower error floor than that of their rate-1/3 parent codes. Nevertheless, good puncturing patterns can only…

Information Theory · Computer Science 2016-11-18 Ioannis Chatzigeorgiou , Miguel R. D. Rodrigues , Ian J. Wassell , Rolando Carrasco