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We introduce several probabilistic quantum algorithms that overcome the normal unitary restrictions in quantum machine learning by leveraging the Linear Combination of Unitaries (LCU) method. Among our investigations are quantum native…

Quantum Physics · Physics 2025-05-19 Jamie Heredge , Maxwell West , Lloyd Hollenberg , Martin Sevior

In the framework of Impagliazzo's five worlds, a distinction is often made between two worlds, one where public-key encryption exists (Cryptomania), and one in which only one-way functions exist (MiniCrypt). However, the boundaries between…

In recent years, achieving verifiable quantum advantage on a NISQ device has emerged as an important open problem in quantum information. The sampling-based quantum advantages are not known to have efficient verification methods. This paper…

Quantum Physics · Physics 2025-10-29 Nai-Hui Chia , Honghao Fu , Fang Song , Penghui Yao

We initiate a systematic study of pseudo-deterministic quantum algorithms. These are quantum algorithms that, for any input, output a canonical solution with high probability. Focusing on the query complexity model, our main contributions…

Quantum Physics · Physics 2026-02-20 Hugo Aaronson , Tom Gur , Jiawei Li

Compact quantum data representations are essential to the emerging field of quantum algorithms for data analysis. We introduce two new data encoding schemes, QCrank and QBArt, which have a high degree of quantum parallelism through…

Quantum Key Distribution (QKD) enables Information-Theoretically Secure (ITS) key exchange, robust even against future quantum computing threats. However, a fundamental limitation of QKD is the requirement for an authenticated classical…

Quantum Physics · Physics 2026-05-07 Nicolas Laurent-Puig , Mina Doosti , Adriano Innocenzi , Eleni Diamanti

A quantum encryption scheme (also called private quantum channel, or state randomization protocol) is a one-time pad for quantum messages. If two parties share a classical random string, one of them can transmit a quantum state to the other…

Quantum Physics · Physics 2007-05-23 Andris Ambainis , Adam Smith

Inevitably, assessing the overall performance of a quantum computer must rely on characterizing some of its elementary constituents and, from this information, formulate a broader statement concerning more complex constructions thereof.…

Quantum Physics · Physics 2019-08-14 Arnaud Carignan-Dugas , Matthew Alexander , Joseph Emerson

Advances in quantum computing make Shor's algorithm for factorising numbers ever more tractable. This threatens the security of any cryptographic system which often relies on the difficulty of factorisation. It also threatens methods based…

Cryptography and Security · Computer Science 2022-02-08 Jon Barton , William J Buchanan , Nikolaos Pitropakis , Sarwar Sayeed , Will Abramson

Quantum Random Access Codes (QRACs) are key tools for a variety of protocols in quantum information theory. These are commonly studied in prepare-and-measure scenarios in which a sender prepares states and a receiver measures them. Here, we…

Quantum Physics · Physics 2019-08-21 Karthik Mohan , Armin Tavakoli , Nicolas Brunner

In a world where Quantum Networks are rapidly becoming a reality, the development of the Quantum Internet is gaining increasing interest. Nevertheless, modern quantum networks are still in the early stages of development and have limited…

In a secure bit commitment protocol involving only classical physics, A commits either a 0 or a 1 to B. If quantum information is used in the protocol, A may be able to commit a state of the form $\alpha \ket{0} + \beta \ket{1}$. If so, she…

Quantum Physics · Physics 2009-10-31 Adrian Kent

Random unitaries are useful in quantum information and related fields, but hard to generate with limited resources. An approximate unitary $k$-design is an ensemble of unitaries with an underlying measure over which the average is close to…

Quantum Physics · Physics 2026-02-09 Nicholas LaRacuente , Felix Leditzky

Our aim is to experimentally study the possibility of distinguishing between quantum sources of randomness--recently proved to be theoretically incomputable--and some well-known computable sources of pseudo-randomness. Incomputability is a…

Quantum Physics · Physics 2009-12-23 Cristian S. Calude , Michael J. Dinneen , Monica Dumitrescu , Karl Svozil

The analysis of quantum algorithms which query random, invertible permutations has been a long-standing challenge in cryptography. Many techniques which apply to random oracles fail, or are not known to generalize to this setting. As a…

Quantum Physics · Physics 2025-09-24 Joseph Carolan

Understanding the complexity of quantum states and circuits is a central challenge in quantum information science, with broad implications in many-body physics, high-energy physics and quantum learning theory. A common way to model the…

Quantum Physics · Physics 2026-05-15 Oxana Shaya , Zoë Holmes , Christoph Hirche , Armando Angrisani

Methods of quantum mechanics promise information-theoretic security for various protocols in cryptography. However, impossibility of some cryptographic applications such as standard bit commitment, oblivious transfer, multiparty secure…

Quantum Physics · Physics 2015-08-03 Muhammad Nadeem

In recent years, new algorithms and cryptographic protocols based on the laws of quantum physics have been designed to outperform classical communication and computation. We show that the quantum world also opens up new perspectives in the…

Quantum Physics · Physics 2010-07-06 S. Perseguers , M. Lewenstein , A. Acín , J. I. Cirac

Many quantum algorithms, to compute some property of a unitary $U$, require access not just to $U$, but to $cU$, the unitary with a control qubit. We show that having access to $cU$ does not help for a large class of quantum problems. For a…

Quantum Physics · Physics 2026-04-27 Ewin Tang , John Wright

We show that concrete hardness assumptions about learning or cloning the output state of a random quantum circuit can be used as the foundation for secure quantum cryptography. In particular, under these assumptions we construct secure…

Quantum Physics · Physics 2025-04-23 Bill Fefferman , Soumik Ghosh , Makrand Sinha , Henry Yuen