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We show that universal quantum computation can be achieved in the standard pure-state circuit model while, at any time, the entanglement entropy of all bipartitions is small---even tending to zero with growing system size. The result is…

Quantum Physics · Physics 2013-04-11 Maarten Van den Nest

Near-term quantum computers are likely to have small depths due to short coherence time and noisy gates, and thus a potential way to use these quantum devices is using a hybrid scheme that interleaves them with classical computers. For…

Quantum Physics · Physics 2025-07-14 Nai-Hui Chia , Kai-Min Chung , Ching-Yi Lai

The "Power of One Qubit" refers to a computational model that has access to only one pure bit of quantum information, along with n qubits in the totally mixed state. This model, though not as powerful as a pure-state quantum computer, is…

Quantum Physics · Physics 2009-11-11 Animesh Datta , Steven T. Flammia , Carlton M. Caves

The recent proliferation of NISQ devices has made it imperative to understand their computational power. In this work, we define and study the complexity class $\textsf{NISQ} $, which is intended to encapsulate problems that can be…

Quantum Physics · Physics 2022-10-14 Sitan Chen , Jordan Cotler , Hsin-Yuan Huang , Jerry Li

The query model (or black-box model) has attracted much attention from the communities of both classical and quantum computing. Usually, quantum advantages are revealed by presenting a quantum algorithm that has a better query complexity…

Quantum Physics · Physics 2020-12-14 Zekun Ye , Lvzhou Li

From the existence of an efficient quantum algorithm for factoring, it is likely that quantum computation is intrinsically more powerful than classical computation. At present, the best upper bound known for the power of quantum computation…

Quantum Physics · Physics 2015-09-14 Ciarán M. Lee , Jonathan Barrett

The possibility to save and process information in fundamentally indistinguishable states is the quantum mechanical resource that is not encountered in classical computing. I demonstrate that, if energy constraints are imposed, this…

Quantum Physics · Physics 2018-02-14 N. A. Sinitsyn

We present a protocol which allows a client to have a server carry out a quantum computation for her such that the client's inputs, outputs and computation remain perfectly private, and where she does not require any quantum computational…

Quantum Physics · Physics 2012-02-22 Anne Broadbent , Joseph Fitzsimons , Elham Kashefi

Establishing an advantage for (white-box) computations by a quantum computer against its classical counterpart is currently a key goal for the quantum computation community. A quantum advantage is achieved once a certain computational…

Quantum Physics · Physics 2024-02-06 Dmitri Maslov , Sergey Bravyi , Felix Tripier , Andrii Maksymov , Joe Latone

Driven by exploring the power of quantum computation with a limited number of qubits, we present a novel complete characterization for space-bounded quantum computation, which encompasses settings with one-sided error (unitary coRQL) and…

Quantum Physics · Physics 2024-05-24 François Le Gall , Yupan Liu , Qisheng Wang

Data-driven decision-making processes increasingly utilize end-to-end learnable deep neural networks to render final decisions. Sometimes, the output of the forward functions in certain layers is determined by the solutions to mathematical…

Machine Learning · Computer Science 2024-12-31 Jianming Pan , Zeqi Ye , Xiao Yang , Xu Yang , Weiqing Liu , Lewen Wang , Jiang Bian

A quantum constraint problem is a frustration-free Hamiltonian problem: given a collection of local operators, is there a state that is in the ground state of each operator simultaneously? It has previously been shown that these problems…

Quantum Physics · Physics 2021-07-22 Alex Meiburg

We use the powerful tools of counting complexity and generic oracles to help understand the limitations of the complexity of quantum computation. We show several results for the probabilistic quantum class BQP. 1. BQP is low for PP, i.e.,…

Computational Complexity · Computer Science 2007-05-23 Lance Fortnow , John D. Rogers

We demonstrate the superior capabilities of the recently proposed Lorentz quantum computer (LQC) compared to conventional quantum computers. We introduce an associated computational complexity class termed bounded-error Lorentz quantum…

Quantum Physics · Physics 2024-09-04 Qi Zhang , Biao Wu

Blind quantum computation (BQC) enables a client with less quantum computational ability to delegate her quantum computation to a server with strong quantum computational power while preserving the client's privacy. Generally, many-qubit…

Quantum Physics · Physics 2022-01-11 Xiaoqian Zhang

Recent work has shown that quantum computers can compute scattering probabilities in massive quantum field theories, with a run time that is polynomial in the number of particles, their energy, and the desired precision. Here we study a…

Quantum Physics · Physics 2018-01-09 Stephen P. Jordan , Hari Krovi , Keith S. M. Lee , John Preskill

We prove the STP=BQP conjecture of Freedman, Hastings and Shokrian-Zini [1], namely that the two-qubit singlet/triplet measurement is quantum computationally universal given only an initial ensemble of maximally mixed single qubits. This…

Quantum Physics · Physics 2023-11-13 Terry Rudolph , Shashank Soyuz Virmani

We present a method to approximate partition functions of quantum systems using mixed-state quantum computation. For positive semi-definite Hamiltonians, our method has expected running-time that is almost linear in $(M/(\epsilon_{\rm…

Quantum Physics · Physics 2021-03-24 Anirban N. Chowdhury , Rolando D. Somma , Yigit Subasi

Quantum computers are widely believed have an advantage over classical computers, and some have even published some empirical evidence that this is the case. However, these publications do not include a rigorous proof of this advantage,…

Computational Complexity · Computer Science 2022-09-22 Jonah Librande

We present a modular error mitigation protocol for running $\mathsf{BQP}$ computations on a quantum computer with time-dependent noise. Utilising existing tools from quantum verification and measurement-based quantum computation, our…

Quantum Physics · Physics 2025-02-06 Joseph Harris , Elham Kashefi