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We present an entirely 2D transversal realization of phase gates at any level of the Clifford hierarchy, and beyond, using non-Abelian surface codes. Our construction encodes a logical qubit in the quantum double $D(G)$ of a non-Abelian…

Quantum Physics · Physics 2026-01-19 Alison Warman , Sakura Schafer-Nameki

The Clifford hierarchy is a foundational concept for universal quantum computation (UQC). It was introduced to show that UQC can be realized via quantum teleportation, given access to certain standard resources. While the full structure of…

Quantum Physics · Physics 2019-08-12 Narayanan Rengaswamy , Robert Calderbank , Henry D. Pfister

Clifford circuits -- i.e. circuits composed of only CNOT, Hadamard, and $\pi/4$ phase gates -- play a central role in the study of quantum computation. However, their computational power is limited: a well-known result of Gottesman and…

Quantum Physics · Physics 2018-06-21 Adam Bouland , Joseph F. Fitzsimons , Dax Enshan Koh

We perform a complete classification of all 56 subgroups of the two-qubit Clifford group containing the two-qubit Pauli group. We provide generators for these groups using gates familiar to the quantum information community and we reference…

Quantum Physics · Physics 2024-09-24 Eric Kubischta , Ian Teixeira

It is advantageous for any quantum processor to support different classes of two-qubit quantum logic gates when compiling quantum circuits, a property that is typically not seen with existing platforms. In particular, access to a gate set…

Standard randomized benchmarking protocols entail sampling from a unitary 2 design, which is not always practical. In this article we examine randomized benchmarking protocols based on subgroups of the Clifford group that are not unitary 2…

Quantum Physics · Physics 2018-06-20 Winton G. Brown , Bryan Eastin

We start by studying the subgroup structures underlying stabilizer circuits. Then we apply our results to provide two normal forms for stabilizer circuits. These forms are computed by induction using simple conjugation rules in the Clifford…

Quantum Physics · Physics 2021-09-03 Marc Bataille

We present an algorithm that decomposes any $n$-qubit Clifford operator into a circuit consisting of three subcircuits containing only CNOT or CPHASE gates with layers of one-qubit gates before and after each of these subcircuits. As with…

Quantum Physics · Physics 2023-10-18 Timothy Proctor , Kevin Young

It is known that the matrices that can be exactly represented by a multiqubit circuit over the Toffoli+Hadamard, Clifford+$T$, or, more generally, Clifford-cyclotomic gate set are precisely the unitary matrices with entries in the ring…

Quantum Physics · Physics 2024-08-13 Andrew N. Glaudell , Neil J. Ross , John van de Wetering , Lia Yeh

Let $n$ be a positive integer divisible by 8. The Clifford-cyclotomic gate set $\mathcal{G}_n$ consists of the Clifford gates, together with a $z$-rotation of order $n$. It is easy to show that, if a circuit over $\mathcal{G}_n$ represents…

Quantum Physics · Physics 2025-08-21 Linh Dinh , Neil J. Ross

Hardware efficient transpilation of quantum circuits to a quantum devices native gateset is essential for the execution of quantum algorithms on noisy quantum computers. Typical quantum devices utilize a gateset with a single two-qubit…

Peres/Mermin arguments about no-hidden variables in quantum mechanics are used for displaying a pair (R, S) of entangling Clifford quantum gates, acting on two qubits. From them, a natural unitary representation of Coxeter/Weyl groups W(D5)…

Quantum Physics · Physics 2011-03-01 Michel Planat

Starting with an explicit framework for designing logical Clifford circuits for CSS codes, we construct logical gates for Hypergraph Product Codes. We first derive symplectic matrices for CNOT, CZ, Phase, and Hadamard operators, which…

Quantum Physics · Physics 2025-09-03 Adway Patra , Alexander Barg

A Hadamard-free Clifford transformation is a circuit composed of quantum Phase (P), CZ, and CNOT gates. It is known that such a circuit can be written as a three-stage computation, -P-CZ-CNOT-, where each stage consists only of gates of the…

Quantum Physics · Physics 2023-10-18 Dmitri Maslov , Willers Yang

A fundamental problem in fault-tolerant quantum computation is the tradeoff between universality and dimensionality, exemplified by the the Bravyi-K\"onig bound for $n$-dimensional topological stabilizer codes. In this work, we extend…

Quantum Physics · Physics 2026-05-21 Ryohei Kobayashi , Guanyu Zhu , Po-Shen Hsin

We show that any $n$-qubit Clifford unitary can be implemented using at most $2n$ multi-qubit joint measurements. All the multi-qubit joint measurements used for implementing the Clifford unitary can be chosen to form at most two sets of…

Quantum Physics · Physics 2026-03-27 Vadym Kliuchnikov , Marcus P. da Silva

Stabilizer circuits play an important role in quantum error correction protocols, and will be vital for ensuring fault tolerance in future quantum hardware. While stabilizer circuits are defined on the Clifford generating set, {H, S, CX},…

Quantum Physics · Physics 2024-05-01 Brendan Reid

We give a general proof for the existence and realizability of Clifford gates in the Ising topological quantum computer. We show that all quantum gates that can be implemented by braiding of Ising anyons are Clifford gates. We find that the…

Quantum Physics · Physics 2009-03-17 Andre Ahlbrecht , Lachezar S. Georgiev , Reinhard F. Werner

The term Clifford group was introduced in 1998 by D. Gottesmann in his investigation of quantum error-correcting codes. The simplest Clifford group in multiqubit quantum computation is generated by a restricted set of unitary Clifford gates…

Quantum Physics · Physics 2018-10-25 J. Tolar

Uniformly controlled one-qubit gates are quantum gates which can be represented as direct sums of two-dimensional unitary operators acting on a single qubit. We present a quantum gate array which implements any n-qubit gate of this type…

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