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Arithmetic operations are an important component of many quantum algorithms. As such, coming up with optimized quantum circuits for these operations leads to more efficient implementations of the corresponding algorithms. In this paper, we…

Quantum Physics · Physics 2026-03-20 Priyanka Mukhopadhyay , Alexandru Gheorghiu , Hari Krovi

In this paper we study the potential of using reinforcement learning (RL) in order to synthesize quantum circuits, while optimizing the T-count and CS-count, of unitaries that are exactly implementable by the Clifford+T and Clifford+CS gate…

Quantum Physics · Physics 2025-12-12 David Kremer , Ali Javadi-Abhari , Priyanka Mukhopadhyay

Among the cost metrics characterizing a quantum circuit, the $T$-count stands out as one of the most crucial as its minimization is particularly important in various areas of quantum computation such as fault-tolerant quantum computing and…

Quantum Physics · Physics 2025-09-17 Vivien Vandaele

We show how to directly and efficiently approximate arbitrary one-qubit unitaries, bypassing the Euler decomposition and the magnitude approximation problem, at the cost of one ancillary qubit. Our technique also applies to approximating…

Quantum Physics · Physics 2026-04-23 Vadym Kliuchnikov , Jendrik Brachter , Marcus P. da Silva

Most work in quantum circuit optimization has been performed in isolation from the results of quantum fault-tolerance. Here we present a polynomial-time algorithm for optimizing quantum circuits that takes the actual implementation of…

Quantum Physics · Physics 2014-11-18 Matthew Amy , Dmitri Maslov , Michele Mosca

We study ancilla-free approximation of single-qubit unitaries $U\in {\rm SU}(2)$ by gate sequences over Clifford+$G$, where $G\in\{T,V\}$ or their generalization. Let $p$ denote the characteristic factor of the gate set (e.g., $p=2$ for…

Quantum Physics · Physics 2025-10-10 Kaoru Sano , Hayata Morisaki , Seiseki Akibue

We consider the problem of synthesizing Clifford quantum circuits for devices with all-to-all qubit connectivity. We approach this task as a reinforcement learning problem in which an agent learns to discover a sequence of elementary…

Quantum Physics · Physics 2026-05-12 Richie Yeung , Aleks Kissinger , Rob Cornish

Clifford group lies at the core of quantum computation -- it underlies quantum error correction, its elements can be used to perform magic state distillation and they form randomized benchmarking protocols, Clifford group is used to study…

Quantum Physics · Physics 2022-08-26 Sergey Bravyi , Joseph A. Latone , Dmitri Maslov

In this work we improve the runtime of recent classical algorithms for strong simulation of quantum circuits composed of Clifford and T gates. The improvement is obtained by establishing a new upper bound on the stabilizer rank of $m$…

Quantum Physics · Physics 2021-12-22 Hammam Qassim , Hakop Pashayan , David Gosset

Simulating quantum circuits classically is an important area of research in quantum information, with applications in computational complexity and validation of quantum devices. One of the state-of-the-art simulators, that of Bravyi et al,…

Quantum Physics · Physics 2019-08-07 Hammam Qassim , Joel J. Wallman , Joseph Emerson

We prove that a unitary matrix has an exact representation over the Clifford+T gate set with local ancillas if and only if its entries are in the ring Z[1/sqrt(2),i]. Moreover, we show that one ancilla always suffices. These facts were…

Quantum Physics · Physics 2013-04-03 Brett Giles , Peter Selinger

We report the achievement of single-qubit gates with sub-part-per-million error rates, in a trapped-ion $^{43}$Ca$^{+}$ hyperfine clock qubit. We explore the speed/fidelity trade-off for gate times $4.4\leq t_{g}\leq35~\mu$s, and benchmark…

Quantum Physics · Physics 2025-06-16 M. C. Smith , A. D. Leu , K. Miyanishi , M. F. Gely , D. M. Lucas

We introduce canonical forms for single qutrit Clifford+T circuits and prove that every single-qutrit Clifford+T operator admits a unique such canonical form. We show that our canonical forms are T-optimal in the sense that among all the…

Quantum Physics · Physics 2019-08-20 Andrew N. Glaudell , Neil J. Ross , Jacob M. Taylor

We propose a normal form for single-qudit gates composed of Clifford and $T$-gates for qudits of odd prime dimension $p\geq 5$. We prove that any single-qudit Clifford+$T$ operator can be re-expressed in this normal form in polynomial time.…

Quantum Physics · Physics 2020-11-17 Akalank Jain , Amolak Ratan Kalra , Shiroman Prakash

We give a quantum approximation scheme (i.e., $(1 + \varepsilon)$-approximation for every $\varepsilon > 0$) for the classical $k$-means clustering problem in the QRAM model with a running time that has only polylogarithmic dependence on…

Quantum Physics · Physics 2025-05-27 Ragesh Jaiswal

The Toffoli gate is an important universal quantum gate, and will alongside the Clifford gates be available in future fault-tolerant quantum computing hardware. Many quantum algorithms rely on performing arbitrarily small single-qubit…

Quantum Physics · Physics 2026-03-13 Christoffer Hindlycke , Jakov Krnic , Jan-Åke Larsson

We introduce a novel algorithm for approximating the logarithm of the determinant of a symmetric positive definite (SPD) matrix. The algorithm is randomized and approximates the traces of a small number of matrix powers of a specially…

Data Structures and Algorithms · Computer Science 2016-09-01 Christos Boutsidis , Petros Drineas , Prabhanjan Kambadur , Eugenia-Maria Kontopoulou , Anastasios Zouzias

Knapsack is one of the most fundamental problems in theoretical computer science. In the $(1 - \epsilon)$-approximation setting, although there is a fine-grained lower bound of $(n + 1 / \epsilon) ^ {2 - o(1)}$ based on the $(\min,…

Data Structures and Algorithms · Computer Science 2025-08-12 Xiao Mao

In fault-tolerant quantum circuit synthesis, T gates supplied via magic states dominate space-time cost, while Clifford gates incur negligible overhead. Conventional flows minimize AND count in an {XOR, AND, NOT} basis as a proxy for T,…

Quantum Physics · Physics 2026-05-18 Hanyu Wang , Mingfei Yu , Xinrui Wu , Jason Cong

We use electronic microwave control methods to implement addressed single-qubit gates with high speed and fidelity, for $^{43}\text{Ca}^{+}$ hyperfine "atomic clock" qubits in a cryogenic (100K) surface trap. For a single qubit, we…

Quantum Physics · Physics 2023-09-21 A. D. Leu , M. F. Gely , M. A. Weber , M. C. Smith , D. P. Nadlinger , D. M. Lucas