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We consider a generic elementary gate sequence which is needed to implement a general quantum gate acting on n qubits -- a unitary transformation with 4^n degrees of freedom. For synthesizing the gate sequence, a method based on the…

Quantum Physics · Physics 2009-11-10 Mikko Mottonen , Juha J. Vartiainen , Ville Bergholm , Martti M. Salomaa

A recurrence scheme is presented to decompose an $n$-qubit unitary gate to the product of no more than $N(N-1)/2$ single qubit gates with small number of controls, where $N = 2^n$. Detailed description of the recurrence steps and formulas…

Quantum Physics · Physics 2013-12-06 Chi-Kwong Li , Diane Pelejo

Executing quantum algorithms over distributed quantum systems requires quantum circuits to be divided into sub-circuits which communicate via entanglement-based teleportation. Naively mapping circuits to qubits over multiple quantum…

Quantum Physics · Physics 2026-02-05 Felix Burt , Kuan-Cheng Chen , Kin K. Leung

We use algebras of pseudodifferential operators on groupoids to study geometric operators on non-compact manifolds and singular spaces. The first step is to establish that the geometric operators are in our algebras. This then leads to…

Spectral Theory · Mathematics 2007-05-23 Robert Lauter , Victor Nistor

Transversal gates play an important role in the theory of fault-tolerant quantum computation due to their simplicity and robustness to noise. By definition, transversal operators do not couple physical subsystems within the same code block.…

Quantum Physics · Physics 2009-11-13 Bryan Eastin , Emanuel Knill

We discuss the partitioning of a quantum system by subsystem separation through unitary block-diagonalization (SSUB) applied to a Fock operator. Our separation can be formulated in a very general way. It can be applied to very different…

Chemical Physics · Physics 2019-05-24 Adrian H. Mühlbach , Markus Reiher

In this work, we report on a novel quantum state reconstruction process based on the disentanglement algorithm. Using variational quantum circuits, we disentangle the quantum state to a product of computational zero states. Inverse…

Quantum Physics · Physics 2024-11-08 Juan Yao

We consider the minimum vertex cover problem having applications in e.g. biochemistry and network security. Quantum annealers can find the optimum solution of such NP-hard problems, given they can be embedded on the hardware. This is often…

Quantum Physics · Physics 2022-04-26 Elijah Pelofske , Georg Hahn , Hristo N. Djidjev

A quantum circuit may be strongly classically simulated with the aid of ZX-calculus by decomposing its $t$ T-gates into a sum of $2^{\alpha t}$ classically computable stabiliser terms. In this paper, we introduce a general procedure to find…

Quantum Physics · Physics 2024-08-13 Matthew Sutcliffe , Aleks Kissinger

In this paper we discuss the problem of decomposition for unbounded $2\times 2$ operator matrices by a pair of complementary invariant graph subspaces. Under mild additional assumptions, we show that such a pair of subspaces decomposes the…

Spectral Theory · Mathematics 2016-08-03 Konstantin A. Makarov , Stephan Schmitz , Albrecht Seelmann

Quantum error correction (QEC) is required for large-scale computation, but incurs a significant resource overhead. Recent advances have shown that by jointly decoding logical qubits in algorithms composed of transversal gates, the number…

The problem of finding and characterizing minimal sets of dequantizers and quantizers applied in the mapping of operators onto functions is considered, for finite-dimensional quantum systems. The general properties of such sets are…

Quantum Physics · Physics 2018-09-26 P. Adam , V. A. Andreev , A. Isar , M. A. Man'ko , V. I. Man'ko

To address the issue of excessive quantum resource requirements in Kuperberg's algorithm for the dihedral hidden subgroup problem, this paper proposes a distributed algorithm based on the function decomposition. By splitting the original…

Quantum Physics · Physics 2025-03-11 Pengyu Yang , Xin Zhang , Song Lin

Dynamical decoupling is a key method to mitigate errors in a quantum mechanical system, and we studied it in a series of papers dealing in particular with the problems arising from unbounded Hamiltonians. The standard bangbang model of…

Mathematical Physics · Physics 2022-11-15 Daniel Burgarth , Paolo Facchi , Robin Hillier

This paper studies the compression of partial differential operators using neural networks. We consider a family of operators, parameterized by a potentially high-dimensional space of coefficients that may vary on a large range of scales.…

Numerical Analysis · Mathematics 2022-03-29 Fabian Kröpfl , Roland Maier , Daniel Peterseim

To run quantum algorithms on emerging gate-model quantum hardware, quantum circuits must be compiled to take into account constraints on the hardware. For near-term hardware, with only limited means to mitigate decoherence, it is critical…

Quantum Physics · Physics 2017-12-22 Davide Venturelli , Minh Do , Eleanor Rieffel , Jeremy Frank

We give a finite presentation by generators and relations of the unitary operators expressible over the {CNOT, T, X} gate set, also known as CNOT-dihedral operators. To this end, we introduce a notion of normal form for CNOT-dihedral…

Quantum Physics · Physics 2019-04-30 Matthew Amy , Jianxin Chen , Neil J. Ross

In this paper we discuss the utilization of Variational Quantum Solver (VQE) and recently introduced Generalized Unitary Coupled Cluster (GUCC) formalism for the diagonalization of downfolded/effective Hamiltonians in active spaces. In…

Quantum Physics · Physics 2020-11-05 Nicholas P. Bauman , Jaroslav Chládek , Libor Veis , Jiří Pittner , Karol Kowalski

Topological quantum computation is a promising technique to achieve large-scale, error-corrected computation. Quantum hardware is used to create a large, 3-dimensional lattice of entangled qubits while performing computation requires…

Quantum Physics · Physics 2014-04-04 Alexandru Paler , Simon J. Devitt , Kae Nemoto , Ilia Polian

Splitting methods have emerged as powerful tools to address complex problems by decomposing them into smaller solvable components. In this work, we develop a general approach to forward-backward splitting methods for solving monotone…

Optimization and Control · Mathematics 2026-04-20 Minh N. Dao , Matthew K. Tam , Thang D. Truong