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Universal logic gates for two quantum bits (qubits) form an essential ingredient of quantum information processing. However, the photons, one of the best candidates for qubits, suffer from the lack of strong nonlinear coupling required for…

Quantum Physics · Physics 2009-11-10 Zhi Zhao , An-Ning Zhang , Yu-Ao Chen , Han Zhang , Jiangfeng Du , Tao Yang , Jian-Wei Pan

Benchmarking methods that can be adapted to multi-qubit systems are essential for assessing the overall or "holistic" performance of nascent quantum processors. The current industry standard is Clifford randomized benchmarking (RB), which…

We show that any pseudoentangled state ensemble with a gap of $t$ bits of entropy requires $\Omega(t)$ non-Clifford gates to prepare. This bound is tight up to polylogarithmic factors if linear-time quantum-secure pseudorandom functions…

Quantum Physics · Physics 2026-03-23 Sabee Grewal , Vishnu Iyer , William Kretschmer , Daniel Liang

Stabilizer states along with Clifford manipulations (unitary transformations and measurements) thereof -- despite being efficiently simulable on a classical computer -- are an important tool in quantum information processing, with…

Quantum Physics · Physics 2026-03-27 Ashlesha Patil , Saikat Guha

A crucial requirement for scalable quantum-information processing is the realization of multiple-qubit quantum gates. Universal multiple-qubit gates can be implemented by a set of universal single qubit gates and any one kind of two-qubit…

Quantum Physics · Physics 2014-11-20 Hai-Ou Li , Gang Cao , Guo-Dong Yu , Ming Xiao , Guang-Can Guo , Hong-Wen Jiang , Guo-Ping Guo

We implement a complete randomized benchmarking protocol on a system of two superconducting qubits. The protocol consists of randomizing over gates in the Clifford group, which experimentally are generated via an improved two-qubit…

We present an efficient quantum algorithm for preparing a pure state on a quantum computer, where the quantum state corresponds to that of a molecular system with a given number $m$ of electrons occupying a given number $n$ of spin…

Quantum Physics · Physics 2009-05-01 Hefeng Wang , S. Ashhab , Franco Nori

The Clifford Hierarchy has been a central topic in quantum computation due to its strong connections with fault-tolerant quantum computation, magic state distillation, and more. Nevertheless, only sections of the hierarchy are fully…

Quantum Physics · Physics 2026-03-13 Luca Bastioni , Samuel Glandon , Tefjol Pllaha , Madison Stewart , Phillip Waitkevich

We construct a polynomial-time classical algorithm that samples from the output distribution of noisy geometrically local Clifford circuits with any product-state input and single-qubit measurements in any basis. Our results apply to…

Quantum Physics · Physics 2026-01-09 Jon Nelson , Joel Rajakumar , Dominik Hangleiter , Michael J. Gullans

In this work we propose a novel numerical approach to decompose general quantum programs in terms of single- and two-qubit quantum gates with a $CNOT$ gate count very close to the current theoretical lower bounds. In particular, it turns…

Quantum Physics · Physics 2022-05-18 Péter Rakyta , Zoltán Zimborás

Motivated by quantum network applications over classical channels, we initiate the study of $n$-party resource states from which LOCC protocols can create EPR-pairs between any $k$ disjoint pairs of parties. We give constructions of such…

Quantum Physics · Physics 2024-05-15 Sergey Bravyi , Yash Sharma , Mario Szegedy , Ronald de Wolf

Finite group extensions offer a natural language to quantum computing. In a nutshell, one roughly describes the action of a quantum computer as consisting of two finite groups of gates: error gates from the general Pauli group P and…

Quantum Physics · Physics 2008-12-18 Michel Planat , Philippe Jorrand

Quantum state discrimination plays a central role in defining the possible and impossible operations through a restricted class of quantum operations. A seminal result by Bennett et al. [Phys. Rev. A 59, 1070 (1999)] demonstrates the…

Quantum Physics · Physics 2025-10-01 Hyukjoon Kwon

We show how to perform measurement-based quantum computing on qudits (high-dimensional quantum systems) using alternative resource states beyond the cluster state. Estimating overheads for gate decomposition, we find that generalizing…

Quantum Physics · Physics 2026-02-13 Alena Romanova , Wolfgang Dür

Compared with a qubit, a qudit (i.e., $d$-level or $d$-state quantum system) provides a larger Hilbert space to store and process information. On the other hand, qudit-based hybrid quantum computing usually requires performing hybrid…

Quantum Physics · Physics 2022-08-30 Qi-Ping Su , Yu Zhang , Liang Bin , Chui-Ping Yang

We introduce the Clifford entropy, a measure of how close an arbitrary unitary is to a Clifford unitary, which generalizes the stabilizer entropy for states. We show that this quantity vanishes if and only if a unitary is Clifford, is…

Quantum Physics · Physics 2025-12-30 Gianluca Cuffaro , Matthew B. Weiss

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

Entangling gates between qubits are a crucial component for performing algorithms in quantum computers. However, any quantum algorithm must ultimately operate on error-protected logical qubits encoded in high-dimensional systems. Typically,…

Minimizing the use of CNOT gates in quantum state preparation is a crucial step in quantum compilation, as they introduce coupling constraints and more noise than single-qubit gates. Reducing the number of CNOT gates can lead to more…

Information Theory · Computer Science 2024-09-05 Hanyu Wang , Bochen Tan , Jason Cong , Giovanni De Micheli

We describe stabilizer states and Clifford group operations using linear operations and quadratic forms over binary vector spaces. We show how the n-qubit Clifford group is isomorphic to a group with an operation that is defined in terms of…

Quantum Physics · Physics 2009-11-10 Jeroen Dehaene , Bart De Moor