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The manipulation of the quantum states of light in linear optical systems has multiple applications in quantum optics and quantum computation. The package QOptCraft gives a collection of methods to solve some of the most usual problems when…

Unitary transformations are the fundamental building blocks of gates and operations in quantum information processing allowing the complete manipulation of quantum systems in a coherent manner. In the case of photons, optical elements that…

Quantum Physics · Physics 2020-01-30 Florian Brandt , Markus Hiekkamäki , Frédéric Bouchard , Marcus Huber , Robert Fickler

This paper presents no new results; its goals are purely pedagogical. A special case of the Cartan Decomposition has found much utility in the field of quantum computing, especially in its sub-field of quantum compiling. This special case…

Quantum Physics · Physics 2007-05-23 Robert R. Tucci

Scalable quantum computation with linear optics was considered to be impossible due to the lack of efficient two-qubit logic gates, despite its ease of implementation of one-qubit gates. Two-qubit gates necessarily need a nonlinear…

Quantum Physics · Physics 2007-05-23 Jonathan P. Dowling , James D. Franson , Hwang Lee , Gerald J. Milburn

Unitary operations are a fundamental component of quantum algorithms, but they seem to be far more useful if given with a "quantum control" as a controlled unitary operation. However, quantum operations are not limited to unitary…

Quantum Physics · Physics 2021-06-16 Qingxiuxiong Dong , Shojun Nakayama , Akihito Soeda , Mio Murao

We describe a decomposition of the Lie group of unitary evolutions for a bipartite quantum system of arbitrary dimensions. The decomposition is based on a recursive procedure which systematically uses the Cartan classification of the…

Quantum Physics · Physics 2015-06-26 Domenico D'Alessandro , Raffaele Romano

Currently available quantum hardware allows for small scale implementations of quantum machine learning algorithms. Such experiments aid the search for applications of quantum computers by benchmarking the near-term feasibility of candidate…

Quantum Physics · Physics 2021-09-08 Michael R. Geller , Zoë Holmes , Patrick J. Coles , Andrew Sornborger

Integrated optics is an engineering solution proposed for exquisite control of photonic quantum information. Here we use silicon photonics and the linear combination of quantum operators scheme to realise a fully programmable two-qubit…

A design framework to implement non-unitary input-output operations to a practical unitary photonic integrated circuit is described. This is achieved by utilising the cosine-sine decomposition to recover the unitarity of the original…

Optics · Physics 2025-01-15 Hussein Talib , Phillip D. Sewell , Ana Vukovic , Sendy Phang

The evolution of quantum light through linear optical devices can be described by the scattering matrix $S$ of the system. For linear optical systems with $m$ possible modes, the evolution of $n$ input photons is given by a unitary matrix…

Quantum Physics · Physics 2025-01-17 Juan Carlos Garcia-Escartin , Vicent Gimeno , Julio José Moyano-Fernández

Qutrits, the triple level quantum systems in various forms, have been proposed for quantum information processing recently. By the methods presented in this paper a bi-photonic qutrit, which is encoded with the polarizations of two photons…

Quantum Physics · Physics 2009-12-08 Qing Lin , Bing He

We suggest an efficient scheme for quantum computation with linear optical elements utilizing "linked" photon states. The linked states are designed according to the particular quantum circuit one wishes to process. Once a linked-state has…

Quantum Physics · Physics 2009-11-10 Nadav Yoran , Benni Reznik

The light's image is the primary source of information carrier in nature. Indeed, a single photon's image possesses a vast information capacity that can be harnessed for quantum information processing. Our scheme for implementing quantum…

Quantum Physics · Physics 2023-03-08 Mohammad Rezai , Jawad A. Salehi

Linear optical operations are fundamental and significant for both quantum mechanics and classical technologies. We demonstrate a non-cascaded approach to perform arbitrary unitary and non-unitary linear operations for N-dimensional…

The polar decomposition for a matrix $A$ is $A=UB$, where $B$ is a positive Hermitian matrix and $U$ is unitary (or, if $A$ is not square, an isometry). This paper shows that the ability to apply a Hamiltonian $\pmatrix{ 0 & A^\dagger \cr A…

Realizing non-unitary transformations on unitary-gate based quantum devices is critically important for simulating a variety of physical problems including open quantum systems and subnormalized quantum states. We present a dilation based…

Using the tool of unitary transformations of the extended receiver we perform simple operations with the non-diagonal elements of the initial sender's density matrix after their transferring to the receiver. These operations are following:…

Quantum Physics · Physics 2020-05-06 A. I. Zenchuk

A general scheme is presented to decompose a $d$-by-$d$ unitary matrix as the product of two-level unitary matrices with additional structure and prescribed determinants. In particular, the decomposition can be done by using two-level…

Quantum Physics · Physics 2013-03-11 Chi-Kwong Li , Rebecca Roberts , Xiaoyan Yin

The characterization of a unitary gate is experimentally accomplished via Quantum Process Tomography, which combines the outcomes of different projective measurements to reconstruct the underlying operator. The process matrix is typically…

Quantum Physics · Physics 2025-09-17 Tareq Jaouni , Francesco Di Colandrea , Lorenzo Amato , Filippo Cardano , Ebrahim Karimi

Structured light, light tailored in its internal degrees of freedom, has become topical in numerous quantum and classical information processing protocols. In this work, we harness the high dimensional nature of structured light modulated…