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Efficient quantum memories will be an essential building block of large scale networked quantum systems and provide a link between flying photonic qubits and atomic or quasi-atomic local quantum processors. To provide a path to scalability…

We develop a framework for learning from noisy quantum experiments in which fault-tolerant devices access uncharacterized systems through noisy couplings. Introducing the complexity class $\textsf{NBQP}$ ("noisy BQP''), we model noisy…

Quantum Physics · Physics 2026-01-15 Jordan Cotler , Weiyuan Gong , Ishaan Kannan

Entropic uncertainty relations are universal quantifiers of fundamental uncertainties of quantum measurements and are widely discussed in the quantum metrology literature. Quantum memory is a phenomenon related to the specific type of…

Here we propose a solid-state quantum memory that does not require spectral holeburning, instead using strong rephasing pulses like traditional photon echo techniques. The memory uses external broadening fields to reduce the optical depth…

Continuous-time stochastic processes pervade everyday experience, and the simulation of models of these processes is of great utility. Classical models of systems operating in continuous-time must typically track an unbounded amount of…

Quantum Physics · Physics 2018-03-05 Thomas J. Elliott , Mile Gu

It has recently been discovered that the optical analogue of a gradient echo in an optically thick material could form the basis of a optical memory that is both completely efficient and noise free. Here we present analytical calculation…

Quantum Physics · Physics 2013-05-29 J. J. Longdell , G. Hétet , M. J. Sellars , P. K. Lam

We use a Quantum Extreme Learning Machine for characterizing and estimating parameters of quantum dynamics generated by a tunable collision model. The input to the learning protocol consists of quantum states produced by successive system…

Quantum Physics · Physics 2026-03-19 Hajar Assil , Abderrahim El Allati , Gian Luca Giorgi

The complete learning of an $n$-qubit quantum state requires samples exponentially in $n$. Several works consider subclasses of quantum states that can be learned in polynomial sample complexity such as stabilizer states or high-temperature…

Quantum Physics · Physics 2023-09-19 Liming Zhao , Naixu Guo , Ming-Xing Luo , Patrick Rebentrost

Simulating a quantum circuit with a classical computer requires exponentially growing resources. Decision diagrams exploit the redundancies in quantum circuit representation to efficiently represent and simulate quantum circuits. But for…

Quantum Physics · Physics 2025-07-08 Yexin Yan , Stefan Hillmich , Robert Wille , Christian Mayr

Quantum machine learning (QML) is often listed as a promising candidate for useful applications of quantum computers, in part due to numerous proofs of possible quantum advantages. A central question is how small a role quantum computers…

Quantum Physics · Physics 2026-01-30 Vasily Bokov , Lisa Kohl , Sebastian Schmitt , Vedran Dunjko

We introduce the problem of *shadow tomography*: given an unknown $D$-dimensional quantum mixed state $\rho$, as well as known two-outcome measurements $E_{1},\ldots,E_{M}$, estimate the probability that $E_{i}$ accepts $\rho$, to within…

Quantum Physics · Physics 2018-11-14 Scott Aaronson

Quantum error mitigation has been proposed as a means to combat unwanted and unavoidable errors in near-term quantum computing without the heavy resource overheads required by fault tolerant schemes. Recently, error mitigation has been…

Quantum Physics · Physics 2024-10-15 Yihui Quek , Daniel Stilck França , Sumeet Khatri , Johannes Jakob Meyer , Jens Eisert

We consider quantum-memory assisted protocols for discriminating quantum channels. We show that for optimal discrimination of memory channels, memory assisted protocols are needed. This leads to a new notion of distance for channels with…

Quantum Physics · Physics 2009-12-21 Giulio Chiribella , Giacomo M. D'Ariano , Paolo Perinotti

We consider a basic model of digital memory where each cell is composed of a reflecting medium with two possible reflectivities. By fixing the mean number of photons irradiated over each memory cell, we show that a non-classical source of…

Quantum Physics · Physics 2015-03-13 Stefano Pirandola

While machine learning has proven to be a powerful data-driven solution to many real-life problems, its use in sensitive domains has been limited due to privacy concerns. A popular approach known as **differential privacy** offers provable…

Machine Learning · Statistics 2016-04-28 Yu-Xiang Wang , Jing Lei , Stephen E. Fienberg

Quantization of neural networks provides benefits of inference in less compute and memory requirements. Previous work in quantization lack two important aspects which this work provides. First almost all previous work in quantization used a…

Computer Vision and Pattern Recognition · Computer Science 2025-12-12 Zia Badar

Quantum kernel methods promise enhanced expressivity for learning structured data, but their usefulness has been limited by kernel concentration and barren plateaus. Both effects are mathematically equivalent and suppress trainability. We…

In the last years, the application of machine learning methods has become increasingly relevant in different fields of physics. One of the most significant subjects in the theory of open quantum systems is the study of the characterization…

Quantum Physics · Physics 2021-03-03 Felipe F. Fanchini , Göktuğ Karpat , Daniel Z. Rossatto , Ariel Norambuena , Raúl Coto

The goal of active learning is to achieve the same accuracy achievable by passive learning, while using much fewer labels. Exponential savings in terms of label complexity have been proved in very special cases, but fundamental lower bounds…

Machine Learning · Statistics 2026-01-01 Yinglun Zhu , Robert Nowak

Quantum memory is important to quantum information processing in many ways: a synchronization device to match various processes within a quantum computer, an identity quantum gate that leaves any state unchanged, and a tool to convert…

Quantum Physics · Physics 2010-04-19 A. I. Lvovsky , B. C. Sanders , W. Tittel