# Obinna AbahNewcastle University | NCL · School of Mathematics, Statistics and Physics

Obinna Abah

Dr. rer. nat.

## About

45

Publications

6,331

Reads

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2,238

Citations

Introduction

Additional affiliations

July 2013 - November 2015

May 2011 - June 2013

Education

May 2000 - October 2004

## Publications

Publications (45)

Thermodynamics originated in the need to understand novel technologies developed by the Industrial Revolution. However, over the centuries, the description of engines, refrigerators, thermal accelerators, and heaters has become so abstract that a direct application of the universal statements to real-life devices is everything but straight forward....

Phase transitions represent a compelling tool for classical and quantum sensing applications. It has been demonstrated that quantum sensors can in principle saturate the Heisenberg scaling, the ultimate precision bound allowed by quantum mechanics, in the limit of large probe number and long measurement time. Due to the critical slowing down, the p...

The African School of Fundamental Physics and Applications, also known as the African School of Physics (ASP), was initiated in 2010, as a three-week biennial event, to offer additional training in fundamental and applied physics to African students with a minimum of three-year university education. Since its inception, ASP has grown to be much mor...

Thermodynamics originated in the need to understand novel technologies developed by the Industrial Revolution. However, over the centuries the description of engines, refrigerators, thermal accelerators, and heaters has become so abstract that a direct application of the universal statements to real-life devices is everything but straight forward....

Quantum metrology shows that by exploiting nonclassical resources it is possible to overcome the fundamental limit of precision found for classical parameter-estimation protocols. The scaling of the quantum Fisher information -- which provides an upper bound to the achievable precision -- with respect to the protocol duration is then of primarily i...

We investigate quantum Otto engine and refrigeration cycles of a time-dependent harmonic oscillator operating under the conditions of maximum $\Omega$-function, a trade-off objective function which represents a compromise between energy benefits and losses for a specific job, for both adiabatic and nonadiabatic (sudden) frequency modulations. We de...

Relativistic quantum systems exhibit unique features not present at lower energies, such as the existence of both particles and antiparticles, and restrictions placed on the system dynamics due to the light cone. In order to understand what impact these relativistic phenomena have on the performance of quantum thermal machines we analyze a quantum...

Relativistic quantum systems exhibit unique features not present at lower energies, such as the existence of both particles and antiparticles, and restrictions placed on the system dynamics due to the light cone. In order to understand what impact these relativistic phenomena have on the performance of quantum thermal machines we analyze a quantum...

Crossing a quantum critical point in finite time challenges the adiabatic condition due to the closing of the energy gap, which ultimately results in the formation of excitations. Such non-adiabatic excitations are typically deemed detrimental in many scenarios, and consequently several strategies have been put forward to circumvent their formation...

The understanding of memory effects arising from the interaction between system and environment is a key for engineering quantum thermodynamic devices beyond the standard Markovian limit. We study the performance of measurement-based thermal machine whose working medium dynamics is subject to backflow of information from the reservoir via collision...

We present the spin quantum Otto machine under different optimization criterion when function either as a heat engine or a refrigerator. We examine the optimal performance of the heat engine and refrigerator depending on their efficiency, output power and maximum entropy production. For heat engine case, we obtain the expression for the upper and l...

We propose two measurement-based schemes to cool a nonlinear mechanical resonator down to energies close to that of its ground state. The protocols rely on projective measurements of a spin degree of freedom, which interacts with the resonator through a Jaynes-Cummings interaction. We show the performance of these cooling schemes, that can be eithe...

We present a fast and robust framework to prepare nonclassical states of a bosonic mode exploiting a coherent exchange of excitations with a two-level system ruled by a Jaynes-Cummings interaction mechanism. Our protocol, which is built on shortcuts to adiabaticity, allows for the generation of arbitrary Fock states of the bosonic mode, as well as...

We investigate the performance of a quantum Otto refrigerator operating in finite time and exploiting local counterdiabatic techniques. We evaluate its coefficient of performance and cooling power when the working medium consists of a quantum harmonic oscillator with a time-dependent frequency. We find that the quantum refrigerator outperforms its...

We propose two measurement-based schemes to cool a nonlinear mechanical resonator down to energies close to that of its ground state. The protocols relies on projective measurements of a spin degree of freedom, which interacts with the resonator through a Jaynes-Cummings interaction. We show the performance of these cooling schemes, that can be eit...

We present a fast and robust framework to prepare non-classical states of a bosonic mode exploiting a coherent exchange of excitations with a two-level system ruled by a Jaynes-Cummings interaction mechanism. Our protocol, which is built on shortcuts to adiabaticity, allows for the generation of arbitrary Fock states of the bosonic mode, as well as...

We investigate the performance of a quantum Otto refrigerator operating in finite time and exploiting local counterdiabatic techniques. We evaluate its coefficient of performance and cooling power when the working medium consists a quantum harmonic oscillator with a time-dependent frequency. We find that the quantum refrigerator outperforms its con...

We quantitatively assess the energetic cost of several well-known control protocols that achieve a finite time adiabatic dynamics, namely counterdiabatic and local counterdiabatic driving, optimal control, and inverse engineering. By employing a cost measure based on the norm of the total driving Hamiltonian, we show that a hierarchy of costs emerg...

We quantitatively assess the energetic cost of several well-known control protocols that achieve a finite time adiabatic dynamics, namely counterdiabatic and local counterdiabatic driving, optimal control, and inverse engineering. By employing a cost measure based on the norm of the total driving Hamiltonian, we show that a hierarchy of costs emerg...

The understanding of memory effects arising from the interaction between system and environment is a key for engineering quantum thermodynamic devices beyond the standard Markovian limit. We study the performance of measurement-based thermal machine whose working medium dynamics is subject to backflow of information from the reservoir via collision...

We consider a finite-time Otto engine operating on a quantum harmonic oscillator and driven by shortcut-to-adiabaticity (STA) techniques to speed up its cycle. We study its efficiency and power when internal friction, time-averaged work, and work fluctuations are used as quantitative figures of merit, showing that time-averaged efficiency and power...

We consider a finite-time Otto engine operating on a quantum harmonic oscillator and driven by shortcut-to-adiabaticity (STA) techniques to speed up its cycle. We study its efficiency and power when internal friction, time-averaged work, and work fluctuations are used as quantitative figures of merit, showing that time-averaged efficiency and power...

We studied the morphological changes of a deformed shallow-water carbonate -that has been dolomitized at an early diagenetic stage in a Neogene fault zone. Orthorhombic rock lithons characterise the structural fabric of the fault zone. Lithons are generated from the intersection of fracture sets. Fractures intersect at approximately 90 +/- 20o and...

Trapped ions in linear Paul traps have been established as a powerful platform for performing experiments in quantum optics, quantum computing, quantum simulation, quantum control, and more recently in quantum thermodynamics. For the latter, modification of the trap geometry can facilitate the study of thermodynamic effects in the motional degrees...

We consider a paradigmatic quantum harmonic Otto engine operating in finite time. We investigate its performance when shortcut-to-adiabaticity techniques are used to speed up its cycle. We compute efficiency and power by taking the energetic cost of the shortcut driving explicitly into account. We analyze in detail three different shortcut methods,...

We investigate the performance of a quantum thermal machine operating in finite time based on shortcut-to-adiabaticity techniques. We compute efficiency and power for a paradigmatic harmonic quantum Otto engine by taking the energetic cost of the shortcut driving explicitly into account. We demonstrate that shortcut-to-adiabaticity machines outperf...

We investigate the performance of a quantum thermal machine operating in finite time based on shortcut-to-adiabaticity techniques. We compute efficiency and power for a quantum harmonic Otto engine by taking the energetic cost of the superadiabatic driving explicitly into account. We further derive generic upper bounds on both quantities, valid for...

We consider a quantum Otto refrigerator cycle of a time-dependent harmonic
oscillator. We investigate the coefficient of performance at maximum figure of
merit for adiabatic and nonadiabatic frequency modulations. We obtain
analytical expressions for the optimal performance both in the high-temperature
(classical) regime and in the low-temperature...

We report the experimental realization of a single-atom heat engine. An ion
is confined in a linear Paul trap with tapered geometry and driven thermally by
coupling it alternately to hot and cold reservoirs. The output power of the
engine is used to drive a harmonic oscillation. From direct measurements of the
ion dynamics, we determine the thermod...

Superconductivity in perovskite, BaKBiO, is studied in the Bardeen–Cooper–Schrieffer (BCS) model, with three-square-well potentials. Components of the new coupling are: the attractive acoustic phonon–electron, optical phonon–electron and repulsive Coulomb interactions. With these in the BCS pairing Hamiltonian, expressions for the superconducting t...

Thermodynamic machines have been studied for two centuries. The rapid advancement in fabrication techniques of the last decades has lead to size reduction from the macroscale to nanoscale. At the nanoscale, quantum properties become important and have thus to be fully taken into account. Quantum heat engines have been the subject of extensive theor...

We consider a quantum Otto cycle for a time-dependent harmonic oscillator coupled to a squeezed thermal reservoir. We show that the efficiency at maximum power increases with the degree of squeezing, surpassing the standard Carnot limit and approaching unity exponentially for large squeezing parameters. We further propose an experimental scheme to...

Analytical calculations of isotope effect exponent of both s-wave and π-phase-shifted s-wave two-band superconductors are presented within the framework of Bogoliubov–Valatin formalism using three-square-well model approach. The effective pairing interaction consists of contributions from the attractive acoustic electron–phonon, optical electron–ph...

We consider quantum heat engines that operate between nonequilibrium stationary reservoirs. We evaluate their maximum efficiency from the positivity of the entropy production and show that it can be expressed in terms of an effective temperature that depends on the nature of the reservoirs. We further compute the efficiency at maximum power for dif...

A two-band BCS-like model in which the mediating interactions arise from both electron–phonon and antiferromagnetically induced interaction as well as ±s-wave gap symmetry has been used to investigate the isotope effect and transition temperature of iron-based superconductors within the Bogoliubov–Valatin approach. Our results show that electron–ph...

We propose an experimental scheme to realize a nanoheat engine with a single ion. An Otto cycle may be implemented by confining the ion in a linear Paul trap with tapered geometry and coupling it to engineered laser reservoirs. The quantum efficiency at maximum power is analytically determined in various regimes. Moreover, Monte Carlo simulations o...

We have derived the expressions for the transition temperature and the isotope effect exponent within the framework of Bogoliubov-Valatin two-band formalism using a linear-energy-dependent electronic density of states assuming a three-square-well potentials model. Our results show that the approach could be used to account for a wide range of value...

The thermodynamic properties of superconducting Dirac electronic systems is analyzed in the vicinity of quantum critical point.
The system is characterized by a quantum critical point at zero doping, such that the critical temperature vanishes below
some finite value of interaction strength. It is found that the specific heat jump of the system lar...

We consider the nonequilibrium work distribution of a quantum oscillator with modulated angular frequency. We examine the discrete-to-continuous transition of the distribution as the temperature and the degree of nonadiabaticity of the frequency transformation are increased. We further develop a perturbative approach to analyze the effect of weak q...

We have investigated the effect of an unconventional pairing mechanism in MgB2 using a two-band model within the framework of Bogoliubov–Valatin formalism. The approach incorporates the intraband s-wave interaction in the s- and p-bands, as well as interband s-wave interaction between them. The analysis assumes that the pairing interaction matrix c...

Superconductivity in magnesium diboride, MgB2, is described within the framework of Bogoliubov–Valatin two-band and two-gap formalism, employing a three-square-well potential model. The expressions for the superconducting transition temperature, Tc, and the isotope exponent, β, are derived. Numerical calculations with the expressions newly reproduc...

## Projects

Project (1)