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Related papers: Learning the quantum algorithm for state overlap

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Quantum networks consist of quantum nodes that are linked by entanglement and quantum information can be transferred from one node to another. Operations can be applied to qubits of local nodes coordinated by classical communication to…

Quantum Physics · Physics 2022-09-16 Bharat Thotakura , Tzu-Chieh Wei

It is well known that Grover's algorithm asymptotically transforms an equal superposition state into an eigenstate (of a given basis). Here, we demonstrate a verification algorithm based on weak measurement which can achieve the same…

Quantum Physics · Physics 2018-05-10 Avinash Dash , Sumit Rout , Bikash K. Behera , Prasanta K. Panigrahi

The rapid progress of physical implementation of quantum computers paved the way of realising the design of tools to help users write quantum programs for any given quantum devices. The physical constraints inherent to the current NISQ…

Emerging Technologies · Computer Science 2020-02-19 Chi Zhang , Yanhao Chen , Yuwei Jin , Wonsun Ahn , Youtao Zhang , Eddy Z. Zhang

We show how techniques from machine learning and optimization can be used to find circuits of photonic quantum computers that perform a desired transformation between input and output states. In the simplest case of a single input state,…

Counting problems such as determining how many bit strings satisfy a given Boolean logic formula are notoriously hard. In many cases, even getting an approximate count is difficult. Here we propose that entanglement, a common concept in…

Statistical Mechanics · Physics 2013-04-03 Claudio Chamon , Eduardo R. Mucciolo

We show that any pseudoentangled state ensemble with a gap of $t$ bits of entropy requires $\Omega(t)$ non-Clifford gates to prepare. This bound is tight up to polylogarithmic factors if linear-time quantum-secure pseudorandom functions…

Quantum Physics · Physics 2026-03-23 Sabee Grewal , Vishnu Iyer , William Kretschmer , Daniel Liang

The qubit routing problem, also known as the swap minimization problem, is a (classical) combinatorial optimization problem that arises in the design of compilers of quantum programs. We study the qubit routing problem from the viewpoint of…

Data Structures and Algorithms · Computer Science 2023-05-16 Takehiro Ito , Naonori Kakimura , Naoyuki Kamiyama , Yusuke Kobayashi , Yoshio Okamoto

Approximating the $k$-th spectral gap $\Delta_k=|\lambda_k-\lambda_{k+1}|$ and the corresponding midpoint $\mu_k=\frac{\lambda_k+\lambda_{k+1}}{2}$ of an $N\times N$ Hermitian matrix with eigenvalues…

Quantum Physics · Physics 2026-05-12 Almudena Carrera Vazquez , Aleksandros Sobczyk

The construction of robust and scalable quantum gates is a uniquely hard problem in the field of quantum computing. Real-world quantum computers suffer from many forms of noise, characterized by the decoherence and relaxation times of a…

Quantum Physics · Physics 2025-07-14 Diego Fuentealba , Jack Dahn , James Steck , Elizabeth Behrman

In this work, we consider the fundamental task of quantum state certification: given copies of an unknown quantum state $\rho$, test whether it matches some target state $\sigma$ or is $\epsilon$-far from it. For certifying $d$-dimensional…

Quantum Physics · Physics 2026-04-10 Chirag Wadhwa , Sitan Chen

We describe a quantum algorithm to estimate the $\alpha$-Renyi entropy of an unknown density matrix $\rho\in\mathcal{C}^{d\times d}$ for $\alpha\neq 1$ by combining the recent technique of quantum singular value transformations with the…

Quantum Physics · Physics 2021-09-01 Sathyawageeswar Subramanian , Min-Hsiu Hsieh

We prove tight lower bounds for the following variant of the counting problem considered by Aaronson, Kothari, Kretschmer, and Thaler (2020). The task is to distinguish whether an input set $x\subseteq [n]$ has size either $k$ or…

Quantum Physics · Physics 2024-05-08 Aleksandrs Belovs , Ansis Rosmanis

A milestone in the field of quantum computing will be solving problems in quantum chemistry and materials faster than state-of-the-art classical methods. The current understanding is that achieving quantum advantage in this area will…

Quantum Physics · Physics 2023-11-08 Guoming Wang , Daniel Stilck França , Ruizhe Zhang , Shuchen Zhu , Peter D. Johnson

Classical probability distributions on sets of sequences can be modeled using quantum states. Here, we do so with a quantum state that is pure and entangled. Because it is entangled, the reduced densities that describe subsystems also carry…

Quantum Physics · Physics 2020-12-10 Tai-Danae Bradley , E. Miles Stoudenmire , John Terilla

Quantum tomography is one of the major challenges of large-scale quantum information research due to the exponential time complexity. In this work, we develop and apply a Bayesian state estimation method to experimentally demonstrate…

Quantum Physics · Physics 2025-11-13 Yang Zhengning , Shihao Ru , Lianzhen Cao , Nikolay Zheludev , Weibo Gao

Understanding algorithmic error accumulation in quantum simulation is crucial due to its fundamental significance and practical applications in simulating quantum many-body system dynamics. Conventional theories typically apply the triangle…

Quantum Physics · Physics 2024-11-11 Boyang Chen , Jue Xu , Qi Zhao , Xiao Yuan

The hopes for scalable quantum computing rely on the "threshold theorem": once the error per qubit per gate is below a certain value, the methods of quantum error correction allow indefinitely long quantum computations. The proof is based…

Quantum Physics · Physics 2014-01-17 M. I. Dyakonov

How many copies of a mixed state $\rho \in \mathbb{C}^{d \times d}$ are needed to learn its spectrum? To date, the best known algorithms for spectrum estimation require as many copies as full state tomography, suggesting the possibility…

Quantum Physics · Physics 2025-04-04 Angelos Pelecanos , Xinyu Tan , Ewin Tang , John Wright

In classical computation, a problem can be solved in multiple steps where calculated results of each step can be copied and used repeatedly. While in quantum computation, it is difficult to realize a similar multi-step computation process…

Quantum Physics · Physics 2023-01-19 Hefeng Wang , Sixia Yu , Hua Xiang

Quantum computing technology is advancing rapidly. Yet, even accounting for these trends, a quantum leap would be needed for quantum computers to meaningfully impact deep learning over the coming decade or two. We arrive at this conclusion…

Quantum Physics · Physics 2025-11-04 Hans Gundlach , Hrvoje Kukina , Jayson Lynch , Neil Thompson