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Variational quantum circuits have recently gained much interest due to their relevance in real-world applications, such as combinatorial optimizations, quantum simulations, and modeling a probability distribution. Despite their huge…

Quantum Physics · Physics 2024-03-11 Chae-Yeun Park , Minhyeok Kang , Joonsuk Huh

We consider quantum circuits consisting of randomly chosen two-local gates and study the number of gates needed for the distribution over measurement outcomes for typical circuit instances to be anti-concentrated, roughly meaning that the…

Quantum Physics · Physics 2022-03-08 Alexander M. Dalzell , Nicholas Hunter-Jones , Fernando G. S. L. Brandão

Two schemes are presented that mitigate the effect of errors and decoherence in short depth quantum circuits. The size of the circuits for which these techniques can be applied is limited by the rate at which the errors in the computation…

Quantum Physics · Physics 2017-11-08 Kristan Temme , Sergey Bravyi , Jay M. Gambetta

In this paper we present an architecture that enables the redesign of large-scale quantum circuits on quantum hardware based on the entangling quantum generative adversarial network (EQ-GAN). Specifically, by prepending a random quantum…

Quantum Physics · Physics 2025-05-19 Runhong He , Ji Guan , Xin Hong , Guolong Cui , Shengbin Wang , Shenggang Ying

We study the problem of minimizing or maximizing the fundamental spectral gap of Schr\"odinger operators on metric graphs with either a convex potential or a ``single-well'' potential on an appropriate specified subset. (In the case of…

Spectral Theory · Mathematics 2024-01-10 Mohammed Ahrami , Zakaria El Allali , Evans M Harrell , James B. Kennedy

The treewidth of a graph is a useful combinatorial measure of how close the graph is to a tree. We prove that a quantum circuit with $T$ gates whose underlying graph has treewidth $d$ can be simulated deterministically in…

Quantum Physics · Physics 2009-07-12 Igor L. Markov , Yaoyun Shi

Characterizing the quantum complexity of local random quantum circuits is a very deep problem with implications to the seemingly disparate fields of quantum information theory, quantum many-body physics and high energy physics. While our…

Quantum Physics · Physics 2021-03-03 Jason Iaconis

We investigate the efficiency of Quantum Adiabatic Optimization when overcoming potential barriers to get from a local to a global minimum. Specifically we look at n qubit systems with symmetric cost functions f:{0, 1}^n->R where the ground…

Quantum Physics · Physics 2016-09-12 Lucas T. Brady , Wim van Dam

Quantum addition based on the quantum Fourier transform can be an integral part of a quantum circuit and proved to be more efficient than the existing classical ripple carry adder. Our study includes identifying the quantum resource…

Random access codes are a type of communication task that is widely used in quantum information science. The optimal average success probability that can be achieved through classical strategies is known for any random access code. However,…

Quantum Physics · Physics 2025-02-27 Máté Farkas , Nikolai Miklin , Armin Tavakoli

Quantum theory promises computational speed-ups over classical approaches. The celebrated Gottesman-Knill Theorem implies that the full power of quantum computation resides in the specific resource of "magic" states -- the secret sauce to…

Quantum Physics · Physics 2025-02-11 Xingjian Zhang , Zhaokai Pan , Guoding Liu

We present a garbling scheme for quantum circuits, thus achieving a decomposable randomized encoding scheme for quantum computation. Specifically, we show how to compute an encoding of a given quantum circuit and quantum input, from which…

Quantum Physics · Physics 2020-11-10 Zvika Brakerski , Henry Yuen

High-fidelity and robust quantum manipulation is the key for scalable quantum computation. Therefore, due to the intrinsic operational robustness, quantum manipulation induced by geometric phases is one of the promising candidates. However,…

Quantum Physics · Physics 2020-09-23 Tao Chen , Pu Shen , Zheng-Yuan Xue

We show that any depth-$d$ circuit for determining whether an $n$-node graph has an $s$-to-$t$ path of length at most $k$ must have size $n^{\Omega(k^{1/d}/d)}$. The previous best circuit size lower bounds for this problem were…

Computational Complexity · Computer Science 2015-09-25 Xi Chen , Igor C. Oliveira , Rocco A. Servedio , Li-Yang Tan

Quantum devices should operate in adherence to quantum physics principles. Quantum random access memory (QRAM), a fundamental component of many essential quantum algorithms for tasks such as linear algebra, data search, and machine…

Quantum Physics · Physics 2024-07-25 Yunfei Wang , Yuri Alexeev , Liang Jiang , Frederic T. Chong , Junyu Liu

A unitary $t$-design is a powerful tool in quantum information science and fundamental physics. Despite its usefulness, only approximate implementations were known for general $t$. In this paper, we provide for the first time quantum…

We investigate the theoretical limits of the effect of the quantum interaction distance on the speed of exact quantum addition circuits. For this study, we exploit graph embedding for quantum circuit analysis. We study a logical mapping of…

Quantum Physics · Physics 2012-09-17 Byung-Soo Choi , Rodney Van Meter

Some physical implementation schemes of quantum computing can apply two-qubit gates only on certain pairs of qubits. These connectivity constraints are commonly viewed as a significant disadvantage. For example, compiling an unrestricted…

Quantum Physics · Physics 2023-09-04 Pei Yuan , Jonathan Allcock , Shengyu Zhang

We benchmark the accuracy of a variational quantum eigensolver based on a finite-depth quantum circuit encoding ground state of local Hamiltonians. We show that in gapped phases, the accuracy improves exponentially with the depth of the…

In the search for quantum advantage with near-term quantum devices, navigating the optimization landscape is significantly hampered by the barren plateaus phenomenon. This study presents a strategy to overcome this obstacle without changing…

Quantum Physics · Physics 2025-03-11 Yuhan Yao , Yoshihiko Hasegawa