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It is a major challenge to construct good quantum codes supporting fault-tolerant (e.g. transversal) non-Clifford gates with low-weight parity-check measurements. In this paper, we construct the first known quantum codes with linear…

Quantum Physics · Physics 2025-10-09 Louis Golowich , Venkatesan Guruswami

Encoding schemes and error-correcting codes are widely used in information technology to improve the reliability of data transmission over real-world communication channels. Quantum information protocols can further enhance the performance…

Reducing the number of non-Clifford quantum gates present in a circuit is an important task for efficiently implementing quantum computations, especially in the fault-tolerant regime. We present a new method for reducing the number of…

Quantum Physics · Physics 2020-08-13 Aleks Kissinger , John van de Wetering

The ability to fault-tolerantly prepare CAT states, also known as multi-qubit GHZ states, is an important primitive for quantum error correction. It is required for Shor-style syndrome extraction, and can also be used as a subroutine for…

Compiling quantum circuits to account for hardware restrictions is an essential part of the quantum computing stack. Circuit compilation allows us to adapt algorithm descriptions into a sequence of operations supported by real quantum…

Quantum Physics · Physics 2025-10-14 Alejandro Villoria , Henning Basold , Alfons Laarman

We use a combination of analytical and numerical techniques to calculate the noise threshold and resource requirements for a linear optical quantum computing scheme based on parity-state encoding. Parity-state encoding is used at the lowest…

Quantum Physics · Physics 2013-05-29 A. J. F. Hayes , H. L. Haselgrove , Alexei Gilchrist , T. C. Ralph

Topological color codes are widely acknowledged as promising candidates for fault-tolerant quantum computing. Neither a two-dimensional nor a three-dimensional topology, however, can provide a universal gate set $\{$H, T, CNOT$\}$, with the…

Quantum Physics · Physics 2024-06-26 Friederike Butt , Sascha Heußen , Manuel Rispler , Markus Müller

Quantum computing is believed to be particularly useful for the simulation of chemistry and materials, among the various applications. In recent years, there have been significant advancements in the development of near-term quantum…

Quantum Physics · Physics 2022-10-12 Guoming Wang , Sukin Sim , Peter D. Johnson

We perform optimal-control-theory calculations to determine the minimum number of two-qubit CNOT gates needed to perform quantum state preparation and unitary operator synthesis for few-qubit systems. By considering all possible gate…

Quantum Physics · Physics 2022-08-24 Sahel Ashhab , Naoki Yamamoto , Fumiki Yoshihara , Kouichi Semba

The initialization of quantum states or Quantum State Preparation (QSP) is a basic subroutine in quantum algorithms. In the worst case, general QSP algorithms are expensive due to the application of multi-controlled gates required to build…

We propose a method for universal fault-tolerant quantum computation using concatenated quantum error correcting codes. Namely, other than computational basis state preparation as required by the DiVincenzo criteria [1], our scheme requires…

Quantum Physics · Physics 2014-04-02 Tomas Jochym-O'Connor , Raymond Laflamme

Efficient state preparation is a challenging and important problem in quantum computing. In this work, we present a recursive state preparation algorithm that combines logarithmic-depth Dicke state circuits with Hamming weight encoders for…

Quantum Physics · Physics 2025-11-17 Sunil Vittal , Anthony Wilkie , Nika Rastegari , Mostafa Atallah , Rebekah Herrman

Quantum circuits currently constitute a dominant model for quantum computation. Our work addresses the problem of constructing quantum circuits to implement an arbitrary given quantum computation, in the special case of two qubits. We…

Quantum Physics · Physics 2009-11-07 Stephen S. Bullock , Igor L. Markov

Data encoding remains a fundamental bottleneck in quantum machine learning, where amplitude encoding of high-dimensional classical vectors into quantum states incurs exponential cost. In this work, we propose a pre-trained tensor-train (TT)…

Quantum Physics · Physics 2026-02-11 Jun Qi , Chao-Han Huck Yang , Pin-Yu Chen , Min-Hsiu Hsieh

State preparation is a process encoding the classical data into the quantum systems. Based on quantum phase estimation, we propose the specific quantum circuits for a deterministic state preparation algorithm and a probabilistic state…

Quantum Physics · Physics 2019-12-12 Jian Zhao , Yu-Chun Wu , Guang-Can Guo , Guo-Ping Guo

With the successful demonstration of transversal CNOTs in many recent experiments, it is the right moment to examine its implications on one of the most critical parts of fault-tolerant computation -- magic state preparation. Using an…

Quantum Physics · Physics 2025-10-30 Nicholas Fazio , Mark Webster , Zhenyu Cai

The rapid pace of recent advancements in numerical computation, notably the rise of GPU and TPU hardware accelerators, have allowed tensor network (TN) algorithms to scale to even larger quantum simulation problems, and to be employed more…

Quantum Physics · Physics 2022-09-02 Manuel S. Rudolph , Jing Chen , Jacob Miller , Atithi Acharya , Alejandro Perdomo-Ortiz

Digital quantum simulation of electron-phonon systems requires truncating infinite phonon levels into $N$ basis states and then encoding them with qubit computational basis. Unary encoding and the more compact binary/Gray encoding are the…

Quantum Physics · Physics 2023-05-04 Weitang Li , Jiajun Ren , Sainan Huai , Tianqi Cai , Zhigang Shuai , Shengyu Zhang

We present a method for optimizing quantum circuit compilation by automating the allocation of auxiliary qubits for multi-qubit gate decompositions. This approach is implemented and evaluated within the high-level quantum programming…

Quantum Physics · Physics 2024-12-31 Evandro C. R. Rosa , Jerusa Marchi , Eduardo I. Duzzioni , Rafael de Santiago