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We present a fault-tolerant universal quantum computing architecture based on a code concatenation of biased-noise qubits and the parity architecture. The parity architecture can be understood as an LDPC code tailored specifically to obtain…

Quantum Physics · Physics 2025-12-01 Anette Messinger , Valentin Torggler , Berend Klaver , Michael Fellner , Wolfgang Lechner

Quantum key distribution (QKD) promises provably secure cryptography, even to attacks from an all-powerful adversary. However, with quantum computing development lagging behind QKD, the assumption that there exists an adversary equipped…

Quantum Physics · Physics 2020-07-01 L. C. G. Govia , D. Bunandar , J. Lin , D. Englund , N. Lütkenhaus , H. Krovi

We propose a scheme for the fault-tolerant implementation of arbitrary Clifford circuits. To achieve this, we extend previous work on flag gadgets for syndrome extraction to a general framework that flags any Clifford circuit. This…

Quantum Physics · Physics 2025-10-10 Benjamin Anker , Milad Marvian

Quantum control in large dimensional Hilbert spaces is essential for realizing the power of quantum information processing. For closed quantum systems the relevant input/output maps are unitary transformations, and the fundamental challenge…

Quantum Physics · Physics 2014-10-17 B. E. Anderson , H. Sosa-Martinez , C. A. Riofrío , I. H. Deutsch , P. S. Jessen

We propose a quantum-classical hybrid algorithm of the power method, here dubbed as quantum power method, to evaluate $\hat{\cal H}^n |\psi\rangle$ with quantum computers, where $n$ is a nonnegative integer, $\hat{\cal H}$ is a…

Quantum Physics · Physics 2021-03-08 Kazuhiro Seki , Seiji Yunoki

We introduce the magic hierarchy, a quantum circuit model that alternates between arbitrary-sized Clifford circuits and constant-depth circuits with two-qubit gates ($\textsf{QNC}^0$). This model unifies existing circuit models, such as…

Quantum Physics · Physics 2025-08-29 Natalie Parham

The challenge in building high-fidelity quantum gates lies in overcoming control errors and decoherence effects caused by the coupling between the quantum system and the external environment. Nonadiabatic holonomic quantum computation uses…

Quantum Physics · Physics 2025-11-04 Yue Heng Liu , Qi Li

The physical limitations of quantum hardware often require nearest-neighbor qubit structures, in which two-qubit gates are required to construct nearest-neighbor quantum circuits. However, two-qubit gates are considered a major cost of…

Quantum Physics · Physics 2022-08-31 Byeongyong Park , Doyeol Ahn

The Variational Quantum Eigensolver approach to the electronic structure problem on a quantum computer involves measurement of the Hamiltonian expectation value. Formally, quantum mechanics allows one to measure all mutually commuting or…

Quantum Physics · Physics 2020-03-17 Tzu-Ching Yen , Vladyslav Verteletskyi , Artur F. Izmaylov

Photonics is the platform of choice to build a modular, easy-to-network quantum computer operating at room temperature. However, no concrete architecture has been presented so far that exploits both the advantages of qubits encoded into…

We propose an adaptive random quantum algorithm to obtain an optimized eigensolver. Specifically, we introduce a general method to parametrize and optimize the probability density function of a random number generator, which is the core of…

Scrambling of quantum information is an important feature at the root of randomization and benchmarking protocols, the onset of quantum chaos, and black-hole physics. Unscrambling this information is possible given perfect knowledge of the…

Quantum Physics · Physics 2024-03-06 Lorenzo Leone , Salvatore F. E. Oliviero , Seth Lloyd , Alioscia Hamma

We demonstrate that the non-Hermitian Hamiltonian approach can be used as a universal tool to design and describe a performance of single photon quantum electrodynamical circuits(cQED). As an example of the validity of this method, we…

Mesoscale and Nanoscale Physics · Physics 2018-12-18 A. N. Sultanov , Ya. S. Greenberg , E. A. Mutsenik , D. K. Pitsun , E. Il'ichev

A computation in adiabatic quantum computing is implemented by traversing a path of nondegenerate eigenstates of a continuous family of Hamiltonians. We introduce a method that traverses a discretized form of the path: At each step we apply…

Quantum Physics · Physics 2009-08-14 S. Boixo , E. Knill , R. D. Somma

In recent years qubit designs such as transmons approached the fidelities of up to 0.999. However, even these devices are still insufficient for realizing quantum error correction requiring better than 0.9999 fidelity. Topologically…

Quantum Physics · Physics 2021-10-13 Andrey R. Klots , Lev B. Ioffe

Variational quantum algorithms (VQAs) are a modern family of quantum algorithms designed to solve optimization problems using a quantum computer. Typically VQAs rely on a feedback loop between the quantum device and a classical optimization…

Quantum Physics · Physics 2022-08-26 Alexey Uvarov

A decision diagram (DD) is a graph-like data structure for homomorphic compression of Boolean and pseudo-Boolean functions. Over the past decades, decision diagrams have been successfully applied to verification, linear algebra, stochastic…

Quantum Physics · Physics 2026-02-23 Arend-Jan Quist , Tim Coopmans , Alfons Laarman

Random Numbers determine the security level of cryptographic applications as they are used to generate padding schemes in the encryption/decryption process as well as used to generate cryptographic keys. This paper utilizes the QKD to…

Cryptography and Security · Computer Science 2014-11-11 Omer K. Jasim , Safia Abbas , El-Sayed M. El-Horbaty , Abdel-Badeeh M. Salem

The Clifford group plays a central role in quantum randomized benchmarking, quantum tomography, and error correction protocols. Here we study the structural properties of this group. We show that any Clifford operator can be uniquely…

Quantum Physics · Physics 2022-04-11 Sergey Bravyi , Dmitri Maslov

We introduce Quantum-Adaptive KS($\varphi$) ($K$ = kickback, $S$ = sandwich), a parameterized three-qubit gate family that structurally embeds the Toffoli (CCX) gate within two additional components: (1)a palindromic Hadamard sandwich on…

Quantum Physics · Physics 2026-05-26 Kripa Sankaranarayanan , Marek Perkowski