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It is the prevailing belief that quantum error correcting techniques will be required to build a utility-scale quantum computer able to perform computations that are out of reach of classical computers. The QECCs that have been most…

Quantum error correction is an essential ingredient for reliable quantum computation for theoretically provable quantum speedup. Topological color codes, one of the quantum error correction codes, have an advantage against the surface codes…

Quantum Physics · Physics 2024-02-02 Yugo Takada , Yusaku Takeuchi , Keisuke Fujii

Classical data encoding is usually treated as a black-box in the oracle-based quantum algorithms. On the other hand, their constructions are crucial for practical algorithm implementations. Here, we open the black-boxes of data encoding and…

Quantum Physics · Physics 2024-04-30 Xiao-Ming Zhang , Xiao Yuan

Accurate, nontrivial quantum operations on many qubits are experimentally challenging. As opposed to the standard approach of compiling larger unitaries into sequences of 2-qubit gates, we propose a protocol on Hamiltonian control fields…

Quantum Physics · Physics 2019-12-02 Koen Groenland , Kareljan Schoutens

Standard approaches to quantum error correction for fault-tolerant quantum computing are based on encoding a single logical qubit into many physical ones, resulting in asymptotically zero encoding rates and therefore huge resource…

Quantum Physics · Physics 2024-09-06 Hayato Goto

We introduce a block encoding method for mapping discrete subgroups to qubits on a quantum computer. This method is applicable to general discrete groups, including crystal-like subgroups such as $\mathbb{BI}$ of $SU(2)$ and $\mathbb{V}$ of…

High Energy Physics - Lattice · Physics 2024-05-22 Henry Lamm , Ying-Ying Li , Jing Shu , Yi-Lin Wang , Bin Xu

The quantum simulation of quantum chemistry is a promising application of quantum computers. However, for N molecular orbitals, the $\mathcal{O}(N^4)$ gate complexity of performing Hamiltonian and unitary Coupled Cluster Trotter steps makes…

Computational Physics · Physics 2022-05-18 Mario Motta , Erika Ye , Jarrod R. McClean , Zhendong Li , Austin J. Minnich , Ryan Babbush , Garnet Kin-Lic Chan

We present two new constructions for the Toffoli gate which substantially reduce resource costs in fault-tolerant quantum computing. The first contribution is a Toffoli gate requiring Clifford operations plus only four $T =…

Quantum Physics · Physics 2013-03-18 Cody Jones

In this short review, I draw attention to new developments in the theory of fault tolerance in quantum computation that may give concrete direction to future work in the development of superconducting qubit systems. The basics of quantum…

Quantum Physics · Physics 2015-05-13 David P. DiVincenzo

While mapping a quantum circuit to the physical layer one has to consider the numerous constraints imposed by the underlying hardware architecture. Connectivity of the physical qubits is one such constraint that restricts two-qubit…

Quantum Physics · Physics 2022-11-14 Vlad Gheorghiu , Jiaxin Huang , Sarah Meng Li , Michele Mosca , Priyanka Mukhopadhyay

Fault-tolerant logic gates will consume a large proportion of the resources of a two-dimensional quantum computing architecture. Here we show how to perform a fault-tolerant non-Clifford gate with the surface code; a quantum…

Quantum Physics · Physics 2021-04-20 Benjamin J. Brown

Estimating the eigenstate properties of quantum systems is a long-standing, challenging problem for both classical and quantum computing. Existing universal quantum algorithms typically rely on ideal and efficient query models (e.g. time…

Quantum Physics · Physics 2026-01-21 Jinzhao Sun , Pei Zeng , Tom Gur , M. S. Kim

There have been significant recent advances in constructing theoretical and practical quantum error correcting codes that function well as quantum memories; however, performing fault-tolerant logical gates on these codes is less studied,…

Quantum Physics · Physics 2025-10-22 Noah Berthusen , Elijah Durso-Sabina

Precise characterization of noisy quantum operations plays an important role for realizing further accurate operations. Quantum tomography is a popular class of characterization methods, and several advanced methods in the class use error…

Quantum Physics · Physics 2025-03-18 Takanori Sugiyama

The threshold theorem promises a path to fault-tolerant quantum computation, provided the physical error rate is below a critical threshold. While transversal gates efficiently implement logical operations, they propagate errors and can…

Quantum Physics · Physics 2026-04-21 Yichen Xu , Yiqing Zhou , James P. Sethna , Eun-Ah Kim

Efficient synthesis of arbitrary quantum states and unitaries from a universal fault-tolerant gate-set e.g. Clifford+T is a key subroutine in quantum computation. As large quantum algorithms feature many qubits that encode coherent quantum…

Quantum Physics · Physics 2024-06-19 Guang Hao Low , Vadym Kliuchnikov , Luke Schaeffer

Quantum algorithms often use quantum RAMs (QRAM) for accessing information stored in a database-like manner. QRAMs have to be fast, resource efficient and fault-tolerant. The latter is often influenced by access speeds, because shorter…

Quantum Physics · Physics 2020-09-16 Alexandru Paler , Oumarou Oumarou , Robert Basmadjian

With the Quantum Singular Value Transformation (QSVT) emerging as a unifying framework for diverse quantum speedups, the efficient construction of block encodings -- their fundamental input model -- has become increasingly crucial. However,…

Quantum Physics · Physics 2025-08-25 Filippo Della Chiara , Martina Nibbi , Yizhi Shen , Roel Van Beeumen

Quantum chemistry provides a target for quantum simulation of considerable scientific interest and industrial importance. The majority of algorithms to date have been based on a second-quantized representation of the electronic structure…

Quantum Physics · Physics 2013-12-17 Borzu Toloui , Peter J. Love

With the development of quantum hardware bringing the error-corrected quantum circuits to the near future, the lack of an efficient polynomial-time decoding algorithms for logical circuits presents a critical bottleneck. While quantum…

Quantum Physics · Physics 2025-04-25 Yiqing Zhou , Chao Wan , Yichen Xu , Jin Peng Zhou , Kilian Q. Weinberger , Eun-Ah Kim