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Understanding the structure of multi-qubit quantum states is essential for both quantum information research and education, yet intuitive visualization beyond the single-qubit Bloch sphere remains challenging. In this work, we propose a…

Quantum Physics · Physics 2026-03-11 Satoru Shoji

We propose several methods for optimizing the number of qubits in a quantum circuit while preserving the number of non-Clifford gates. One of our approaches consists in reversing, as much as possible, the gadgetization of Hadamard gates,…

Quantum Physics · Physics 2024-07-16 Vivien Vandaele

We propose to represent both $n$--qubits and quantum gates acting on them as elements in the complex Clifford algebra defined on a complex vector space of dimension $2n.$ In this framework, the Dirac formalism can be realized in…

Quantum Physics · Physics 2022-03-04 Jaroslav Hrdina , Ales Navrat , Petr Vasik

In quantum mechanics, geometry has been demonstrated as a useful tool for inferring non-classical behaviors and exotic properties of quantum systems. One standard approach to illustrate the geometry of quantum systems is to project the…

Graphical calculi for representing interacting quantum systems serve a number of purposes: compositionally, intuitive graphical reasoning, and a logical underpinning for automation. The power of these calculi stems from the fact that they…

Logic in Computer Science · Computer Science 2011-03-17 Bob Coecke , Aleks Kissinger , Alex Merry , Shibdas Roy

Visual methods are of great utility in understanding and interpreting quantum mechanics at all levels of understanding. The Bloch sphere, for example, is an invaluable and widely used tool for visualising quantum dynamics of a two level…

Quantum Physics · Physics 2023-04-26 Max Z. Festenstein

As a fundamental metric for quantifying quantum advantage in non-local games, the quantum chromatic number reveals the power of entanglement in distributed tasks. In this paper, we investigate this parameter for $q$-ary Hamming graphs and a…

Combinatorics · Mathematics 2026-03-12 Xiwang Cao , Keqin Feng , Hexiang Huang , Yulin Yang , Zihao Zhang

The paper describes an algorithm for semantic representation of behavioral contexts relative to a dichotomic decision alternative. The contexts are represented as quantum qubit states in two-dimensional Hilbert space visualized as points on…

Neurons and Cognition · Quantitative Biology 2020-12-23 Ilya A. Surov

Geometric algebra is a mathematical structure that is inherent in any metric vector space, and defined by the requirement that the metric tensor is given by the scalar part of the product of vectors. It provides a natural framework in which…

Quantum Physics · Physics 2009-11-10 Timothy F. Havel , Chris J. L. Doran

We give a sound and complete equational theory for 3-qubit quantum circuits over the Toffoli-Hadamard gate set { X, CX, CCX, H }. That is, we introduce a collection of true equations among Toffoli-Hadamard circuits on three qubits that is…

Quantum Physics · Physics 2024-08-13 Matthew Amy , Neil J. Ross , Scott Wesley

We show that an n-th root of the Walsh-Hadamard transform (obtained from the Hadamard gate and a cyclic permutation of the qubits), together with two diagonal matrices, namely a local qubit-flip (for a fixed but arbitrary qubit) and a…

Quantum Physics · Physics 2007-05-23 Simone Severini

The properties of the geometric phases between three quantum states are investigated in a high-dimensional Hilbert space using the Majorana representation of symmetric quantum states. We found that the geometric phases between the three…

Quantum Physics · Physics 2012-04-18 Shuhei Tamate , Kazuhisa Ogawa , Masao Kitano

Quantum logic decomposition refers to decomposing a given quantum gate to a set of physically implementable gates. An approach has been presented to decompose arbitrary diagonal quantum gates to a set of multiplexed-rotation gates around z…

Emerging Technologies · Computer Science 2015-12-14 Mahboobeh Houshmand , Morteza Saheb Zamani , Mehdi Sedighi , Mona Arabzadeh

The geometry of the generalized Bloch sphere $\Omega_3$, the state space of a qutrit, is studied. Closed form expressions for $\Omega_3$, its boundary $\partial \Omega_3$, and the set of extremals $\Omega_3^{\rm ext}$ are obtained by use of…

Quantum Physics · Physics 2016-03-22 Sandeep K. Goyal , B. Neethi Simon , Rajeev Singh , Sudhavathani Simon

The ZH-calculus is a complete graphical calculus for linear maps between qubits that admits a straightforward encoding of hypergraph states and circuits arising from the Toffoli+Hadamard gate set. In this paper, we establish a…

Quantum Physics · Physics 2021-09-07 Louis Lemonnier , John van de Wetering , Aleks Kissinger

Two-level quantum systems, qubits, are not the only basis for quantum computation. Advantages exist in using qudits, d-level quantum systems, as the basic carrier of quantum information. We show that color codes, a class of topological…

Quantum Physics · Physics 2015-08-11 Fern H. E. Watson , Earl T. Campbell , Hussain Anwar , Dan E. Browne

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

Exterior calculus with its three operations meet, join and hodge star complement, is used for the representation of fermion-hole systems and for fermionic analogues of logical gates. Two different schemes that implement fermionic quantum…

Quantum Physics · Physics 2018-11-14 A. Vourdas

It has been shown that non-stabilizer eigenstates of permutation gates are appropriate for allowing $d$-dimensional universal quantum computing (uqc) based on minimal informationally complete POVMs. The relevant quantum gates may be built…

Geometric Topology · Mathematics 2019-02-20 Michel Planat , Raymond Aschheim , Marcelo M. Amaral , Klee Irwin

We consider a ZX-calculus augmented with triangle nodes which is well-suited to reason on the so-called Toffoli-Hadamard fragment of quantum mechanics. We precisely show the form of the matrices it represents, and we provide an…

Quantum Physics · Physics 2019-01-30 Renaud Vilmart