# Ilya SinayskiyUniversity of KwaZulu-Natal, Westvile, Durban, South Africa · School of Chemistry and Physics

Ilya Sinayskiy

PhD

## About

94

Publications

32,012

Reads

**How we measure 'reads'**

A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more

2,865

Citations

Introduction

**Skills and Expertise**

## Publications

Publications (94)

A wellknown approach to describe the dynamics of an open quantum system is to compute the master equation evolving the reduced density matrix of the system. This approach plays an important role in describing excitation transfer through photosynthetic light harvesting complexes (LHCs). The hierarchical equations of motion (HEOM) was adapted by Ishi...

In the design of quantum devices, it is crucial to account for the interaction between qubits and their environment to understand and improve the coherence and stability of the quantum states. This is especially prevalent in Noisy Intermediate Scale Quantum (NISQ) devices in which the qubit states quickly decay through processes of relaxation and d...

There is an intrinsic link between operations that can be performed on a quantum computer and kernel methods. This has inspired the development of quantum-kernel-based classifiers that exploit the ability of quantum computers to efficiently perform operations in large Hilbert spaces. This work performs a proof of principle demonstration of a quantu...

A well-known approach to describe the dynamics of an open quantum system is to compute the master equation evolving the reduced density matrix of the system. This approach plays an important role in describing excitation transfer through photosynthetic light harvesting complexes (LHCs). The hierarchical equations of motion (HEOM) was adapted by Ish...

The SARS-CoV-2 pandemic has added new urgency to the study of viral mechanisms of infection. But while vaccines offer a measure of protection against this specific outbreak, a new era of pandemics has been predicted. In addition to this, COVID-19 has drawn attention to post-viral syndromes and the healthcare burden they entail. It seems integral th...

The rapid identification and isolation of infected individuals remains a key strategy for controlling the spread of SARS-CoV-2. Frequent testing of populations to detect infection early in asymptomatic or presymptomatic individuals can be a powerful tool for intercepting transmission, especially when the viral prevalence is low. However, RT-PCR tes...

Noisy Intermediate Scale Quantum (NISQ) devices have been proposed as a versatile tool for simulating open quantum systems. Recently, the use of NISQ devices as simulators for non-Markovian open quantum systems has helped verify the current descriptions of non-Markovianity in quantum physics. In this work, convex mixtures of channels are simulated...

Finding solutions to systems of linear equations is a common prob\-lem in many areas of science and engineering, with much potential for a speedup on quantum devices. While the Harrow-Hassidim-Lloyd (HHL) quantum algorithm yields up to an exponential speed-up over classical algorithms in some cases, it requires a fault-tolerant quantum computer, wh...

Variational Hybrid Quantum Classical Algorithms (VHQCAs) are a class of quantum algorithms intended to run on noisy intermediate-scale quantum (NISQ) devices. These algorithms employ a parameterized quantum circuit (ansatz) and a quantum-classical feedback loop. A classical device is used to optimize the parameters in order to minimize a cost funct...

Variational hybrid quantum classical algorithms are a class of quantum algorithms intended to run on noisy intermediate-scale quantum (NISQ) devices. These algorithms employ a parameterized quantum circuit (ansatz) and a quantum-classical feedback loop. A classical device is used to optimize the parameters in order to minimize a cost function that...

The rapid identification and isolation of infected individuals remains a key strategy for controlling the spread of SARS-CoV-2. Frequent testing of populations to detect infection early in asymptomatic or presymptomatic individuals can be a powerful tool for intercepting transmission, especially when the viral prevalence is low. However, RT-PCR tes...

Some of the oldest and most important applications of thermodynamics are operations of refrigeration as well as production of useful energy. Part of the efforts to understand and develop thermodynamics in the quantum regime have been focusing on harnessing quantum effects to such operations. In this review, we present the recent developments regard...

Objectives
To investigate introduction and understand the early transmission dynamics of the SARS-CoV-2 in South-Africa, we formed the Network for Genomic Surveillance in South Africa (NGS-SA).
Design
Here, we present the first results of this effort, which is a molecular epidemiological study of the first twenty-one SARS-CoV-2 whole genomes sampl...

The entropy production in dissipative processes is the essence of the arrow of time and the second law of thermodynamics. For dissipation of quantum systems, it was recently shown that the entropy production contains indeed two contributions: a classical one and a quantum one. Here we show that for degenerate (or near-degenerate) quantum systems th...

The performances of quantum thermometry in thermal equilibrium together with the output power of certain class of quantum engines share a common characteristic: both are determined by the heat capacity of the probe or working medium. After noticing that the heat capacity of spin ensembles can be significantly modified by collective coupling with a...

Open quantum walks (OQWs) describe a quantum walker on an underlying graph whose dynamics is purely driven by dissipation and decoherence. Mathematically, they are formulated as completely positive trace preserving (CPTP) maps on the space of density matrices for the walker on the graph. Any microscopically derived OQW must include the possibility...

Some of the oldest and most important applications of thermodynamics are operations of refrigeration as well as production of useful energy. Part of the efforts to understand and develop thermodynamics in the quantum regime have been focusing on harnessing quantum effects to such operations. In this review we present the recent developments regardi...

Background: The emergence of a novel coronavirus, SARS-CoV-2, in December 2019, progressed to become a world pandemic in a few months and reached South Africa at the beginning of March. To investigate introduction and understand the early transmission dynamics of the virus, we formed the South African Network for Genomics Surveillance of COVID (SAN...

The study of memory effects in quantum channels helps in developing characterization methods for open quantum systems and strategies for quantum error correction. Two main sets of channels exist, corresponding to system dynamics with no memory (Markovian) and with memory (non-Markovian). Interestingly, these sets have a nonconvex geometry, allowing...

The performances of quantum thermometry in thermal equilibrium together with the output power of certain class of quantum engines share a common characteristic: both are determined by the heat capacity of the probe or working medium. After noticing that the heat capacity of spin ensembles can be significantly modified by collective coupling with a...

Rich quantum effects emerge when several quantum systems are indistinguishable from the point of view of the bath they interact with. In particular, delocalized excitations corresponding to coherent superposition of excited states (reminiscent of double slit experiments or beam splitters in interferometers) appear and change drastically the dynamic...

One of the stunning consequences of quantum correlations in thermodynamics is the reversal of the arrow of time, recently shown experimentally in Micadei et al. [Nat. Commun. 10, 2456 (2019)], and manifesting itself by a reversal of the heat flow (from the cold system to the hot one). Here, we show that contrary to what could have been expected, he...

The entropy production in dissipative processes is the essence of thermodynamics and also of the arrow of time. For dissipation of quantum systems, it was recently shown that the entropy production contains indeed two contributions: a classical one and a quantum one. Here we show that for degenerate (or near-degenerate) quantum systems there are ad...

The entropy production in dissipative processes is the essence of thermodynamics and also of the arrow of time. It was recently shown that in dissipation of quantum systems, the entropy production contains two contributions: a classical one and a quantum one. Here we show that for degenerate (or near-degenerate) quantum systems there are additional...

Rich quantum effects emerge when several quantum systems are indistinguishable from the point of view of the bath they interact with. In particular, delocalised excitations corresponding to coherent superposition of excited states (reminiscent of double slit experiments or beam splitters in interferometers) appear and change drastically the dynamic...

Rich quantum effects emerge when several quantum systems are indistinguishable from the point of view of the bath they interact with. In particular, delocalised excitations corresponding to coherent superposition of excited states appear and change drastically the dynamics and steady state of the systems. Such phenomena, present interesting propert...

The study of memory effects in quantum channels helps in developing characterization methods for open quantum systems and strategies for quantum error correction. Two main sets of channels exist, corresponding to system dynamics with no memory (Markovian) and with memory (non-Markovian). Interestingly, these sets have a non-convex geometry, allowin...

Open quantum walks (OQWs) describe a quantum walker on an underlying graph whose dynamics is purely driven by dissipation and decoherence. Mathematically, they are formulated as completely positive trace preserving (CPTP) maps on the space of density matrices for the quantum walker on the graph. A microscopic derivation of the open quantum walks ha...

The computational cost of preparing a quantum state can be substantial depending on the structure of data to be encoded. Many quantum algorithms require repeated sampling to find the answer, mandating reconstruction of the same input state for every execution of an algorithm. Thus, the advantage of quantum computation can diminish due to redundant...

One of the stunning consequences of quantum correlations in thermodynamics is the reversal of the arrow of time, recently shown experimentally in [K. Micadei, et al., Nat. Commun. 10:2456 (2019)], and manifesting itself by a reversal of the heat flow (from the cold system to the hot one). Here, we show that contrary to what could have been expected...

One of the stunning consequences of quantum correlations in thermodynamics is the reversal of the arrow of time, recently shown experimentally in [K. Micadei, et al., Nat. Commun. 10:2456 (2019)], and manifesting itself by a reversal of the heat flow (from the cold system to the hot one). Here, we show that contrary to what could have been expected...

The unavoidable interaction of a quantum system with its surrounding environment (its bath) is not always detrimental for quantum properties. For instance, under some specific conditions (that we identify as indistinguishability), a many-body system can gain internal coherences thanks to the interaction with its bath. The most famous consequence of...

We consider a central fermion strongly interacting with a surrounding mesoscopic bath of fermions which is weakly coupled to a Markovian bath of fermions. The master equation of the system consisting of the central fermion and the mesoscopic bath is derived, and based on this master equation, the reduced dynamics and thermalization of the central f...

Free-space quantum communication technology has made significant advancements over the years. However, to achieve a global quantum network there are still obstacles to overcome. To date, free-space quantum communication channels have been faced with challenges related to losses in the quantum channel, security, and low data rates. Classical machine...

Abstract One of the principal objectives of quantum thermodynamics is to explore quantum effects and their potential beneficial role in thermodynamic tasks like work extraction or refrigeration. So far, even though several papers have already shown that quantum effect could indeed bring quantum advantages, a global and deeper understanding is still...

The computational cost of preparing an input quantum state can be significant depending on the structure of data to be encoded. Many quantum algorithms require repeated sampling to find the answer, mandating reconstruction of the same input state for every execution of an algorithm. Thus, the advantage of quantum information processing can diminish...

Open quantum walks (OQWs) are a class of quantum walks, which are purely driven by the interaction with the dissipative environment. In this paper, we review theoretical advances on the foundations of discrete time OQWs, continuous time OQWs and a scaling limit of OQWs called open quantum Brownian motion. The main focus of the review is on the resu...

Free-space quantum communication faces challenges related to losses in the transmission channel. Machine learning is resourceful for monitoring these channels. Here, supervised learning was used to predict the atmospheric strength of the channel.

Heat exchanges are the essence of Thermodynamics. In order to investigate non-equilibrium effects like quantum coherence and correlations in heat flows we introduce the concept of apparent temperature. Its definition is based on the expression of the heat flow between out-of-equilibrium quantum systems. Such apparent temperatures contain crucial in...

A model of non-reversal quantum walk is introduced. The process is introduced in 1D and 2D using the formalism of open quantum walks (OQWs). In such a walk, a particle cannot go back to previously visited sites but it can jump on the same site or move to a new site. Examples of some non-reversal quantum trajectories and distributions are given and...

Biological systems are dynamical, constantly exchanging energy and matter with the environment in order to maintain the non-equilibrium state synonymous with living. Developments in observational techniques have allowed us to study biological dynamics on increasingly small scales. Such studies have revealed evidence of quantum mechanical effects, w...

The development of the radical pair mechanism has allowed for theoretical explanation of the fact that magnetic fields are observed to have an effect on chemical reactions. The mechanism describes how an external magnetic field can alter chemical yields by interacting with the spin state of a pair of radicals. In the field of quantum biology, there...

The application of Thermodynamics to quantum systems have been arising great hopes and expectations in regard to thermodynamic tasks - work or energy extraction, and refrigeration. For such tasks, enhancements based on genuine quantum features like coherence and quantum correlations have been recently reported. However, little is known about the re...

In contrast to semi-classical refrigerators powered by ideal external work, quantum autonomous refrigerators do not benefit from external work or control and find their source of energy in ancillary systems. Frequently, the ancillary system considered is a (third) thermal bath. The refrigerator is then powered only by heat, limiting its performance...

DOI:https://doi.org/10.1103/PhysRevA.95.069905

DOI:https://doi.org/10.1103/PhysRevA.95.069904

Open Quantum Brownian motion describes a Quantum Brownian particle with an additional internal degree of freedom.The quantum master equation for a free Open Quantum Brownian walker with two-dimensional internal degree of freedom interacting decoherently with the dissipative environment is derived. Using the analytical solution for the moments of th...

A physicochemical description of life and its emergence is one of the greatest open problems in science. Life is made of molecules described fundamentally by quantum theory. The identification of quantum effects in primitive organisms such as bacteria [1,2] has resulted in the successful application of open quantum systems models to energy and char...

We give an algorithm for prediction on a quantum computer which is based on a linear regression model with least-squares optimization. In contrast to related previous contributions suffering from the problem of reading out the optimal parameters of the fit, our scheme focuses on the machine-learning task of guessing the output corresponding to a ne...

We present an algorithmic method for the digital quantum simulation of many-body locally-indivisible non-Markovian open quantum systems. It consists of two parts: Firstly, a Suzuki-Lie-Trotter decomposition of the k-local global system propagator into the product of strictly k-local propagators, which may not be quantum channels, and secondly, an a...

The force estimation problem in Quantum Metrology with an arbitrary non-Markovian bath is considered. No assumptions are made on the bath spectrum and coupling strength with the probe. Considering the natural global unitary evolution of both bath and probe and assuming initial global Gaussian states we are able to solve the main issues of any quant...

We give an algorithm that solves the problem of pattern classification on a quantum computer, effectively performing linear regression with least squares optimisation. Opposed to related previous contributions suffering from the problem of reading out the optimal parameters of the fit, our scheme focuses on prediction for machine learning tasks and...

Open Quantum Walks (OQWs) are exclusively driven by dissipation and are
formulated as completely positive trace preserving (CPTP) maps on underlying
graphs. The microscopic derivation of discrete and continuous in time OQWs is
presented. It is assumed that connected nodes are weakly interacting via a
common bath. The resulting reduced master equati...

The microscopic derivation of a new type of Brownian motion, namely open quantum Brownian motion (OQBM) is presented. The quantum master equation for OQBM is derived for a weakly driven system interacting with a decoherent environment. Examples of the dynamics for initial Gaussian and non-Gaussian distributions are presented. Both examples demonstr...

We consider the problem of constructing a “universal set” of Markovian processes, such that any Markovian open quantum system, described by a one-parameter semigroup of quantum channels, can be simulated through sequential simulations of processes from the universal set. In particular, for quantum systems of dimension $d$, we explicitly construct a...

Since the emergence of oxygenic photosynthesis, living systems have developed protective mechanisms against reactive oxygen species. During charge separation in photosynthetic reaction centres, triplet states can react with molecular oxygen generating destructive singlet oxygen. The triplet product yield in bacteria is observed to be reduced by wea...

It is well known that for certain tasks, quantum computing outperforms
classical computing. A growing number of contributions try to use this
advantage in order to improve or extend classical machine learning algorithms
by methods of quantum information theory. This paper gives a brief introduction
into quantum machine learning using the example of...

Perceptrons are the basic computational unit of artificial neural networks,
as they model the activation mechanism of an output neuron due to incoming
signals from its neighbours. As linear classifiers, they play an important role
in the foundations of machine learning. In the context of the emerging field of
quantum machine learning, several attem...

An open quantum walk approach to the implementation of a dissipative quantum computing scheme is presented. The formalism is demonstrated for the example of an open quantum walk implementation of a 3 qubit quantum circuit consisting of 10 gates.

Machine learning algorithms learn a desired input-output relation from
examples in order to interpret new inputs. This is important for tasks such as
image and speech recognition or strategy optimisation, with growing
applications in the IT industry. In the last couple of years, researchers
investigated if quantum computing can help to improve clas...

With the overwhelming success in the field of quantum information in the last
decades, the "quest" for a Quantum Neural Network (QNN) model began in order to
combine quantum computing with the striking properties of neural computing.
This article presents a systematic approach to QNN research, which so far
consists of a conglomeration of ideas and...

A quantum optical implementation of the recently proposed open quantum walks (OQWs) is suggested. In the presented quantum optical scheme a two level atom plays the role of the "walker" and the Fock states of the cavity mode correspond to the lattice sites of the OQW. Using the small unitary rotations approach the effective dynamics of the system i...

A quantum algorithm is presented for the simulation of arbitrary Markovian
dynamics of a qubit, described by a semigroup of single qubit quantum channels
$\{T_t\}$ specified by an arbitrary generator $\mathcal{L}$. This algorithm
requires only single qubit and CNOT gates and approximates the channel $T_t =
e^{t\mathcal{L}}$ up to arbitrary accuracy...

Quantum walks have been shown to be fruitful tools in analysing the dynamic
properties of quantum systems. This article proposes to use quantum walks as an
approach to Quantum Neural Networks (QNNs). QNNs replace binary McCulloch-Pitts
neurons with a qubit in order to use the advantages of quantum computing in
neural networks. A quantum walk on the...

A new model of quantum random walks is introduced, on lattices as well as on nite graphs. These quantum random walks take into account the behavior of open quantum systems. They are the exact quantum analogue of classical Markov chains. We explore the \quantum trajectory" point of view on these quantum random walks, that is, we show that measuring...

A model of an arbitrary spin coupled to a bath of spins 1/2 in a star
configuration is considered. The exact reduced dynamics of the central spin is
found for the case of non-correlated initial conditions of the system and the
bath. The exact solution is used to test two approximation techniques, namely,
the Nakajima-Zwanzig projection operator tec...

An open quantum walk formalism for dissipative quantum computing is presented. The approach is illustrated with the examples of the Toffoli gate and the Quantum Fourier Transform for 3 and 4 qubits. It is shown that the algorithms based on the open quantum walk formalism are more efficient than the canonical dissipative quantum computing approach....

Recibido el 24 de enero de 2011; aceptado el 24 de marzo de 2011 The dynamics of simple qubit systems in a chain configuration coupled at both ends to separate bosonic baths at different temperatures is studied. An exact analytical solution of the master equation in the Born-Markov approximation for the reduced density matrix of the qubit system is...

A universal definition of non-Markovianity for open systems dynamics is
proposed. It is extended from the classical definition to the quantum realm by
showing that a `transition' from the Markov to the non-Markov regime occurs
when the correlations between the system and the environment, generated by
their joint evolution, can no longer be neglecte...

A system of two coupled oscillators, each of them coupled to an independent reservoir, is analysed. The analytical solution of the non-rotating wave master equation is obtained in the high-temperature and weak coupling limits. No thermal entanglement is found in the high-temperature limit. In the weak coupling limit the system converges to an entan...