In this thesis, different aspects of the quantum Szilard engine are studied using the configuration interaction method. The engine is modelled as a one-dimensional infinite well. The effects of a contact-interaction are examined and it is found that attractive contact-interactions can improve the work output at certain temperatures of an engine that has bosons as a working medium. The role of impurities in the engine is investigated and found to have a large impact on the low-temperature behaviour of the engine. Dynamics of a single-particle engine are considered in order to identify finite-speed effects in the engine's cycle.
In this thesis, different aspects of the quantum Szilard engine are studied using the configuration interaction method. The engine is modelled as a one-dimensional infinite well. The effects of a contact-interaction are examined and it is found that attractive contact-interactions can improve the work output at certain temperatures of an engine that has bosons as a working medium. The role of impurities in the engine is investigated and found to have a large impact on the low-temperature behaviour of the engine. Dynamics of a single-particle engine are considered in order to identify finite-speed effects in the engine's cycle.
In a classic thought experiment, Szilard suggested a heat engine where a single particle, for example an atom or a molecule, is confined in a container coupled to a single heat bath. The container can be separated into two parts by a moveable wall acting as a piston. In a single cycle of the engine, work can be extracted from the information on which side of the piston the particle resides. The work output is consistent with Landauers principle that the erasure of one bit of information costs the entropy kB ln 2, exemplifying the fundamental relation between work, heat and information. Here we apply the concept of the Szilard engine to a fully interacting quantum many-body system. We find that a working medium of a number of bosons (larger or equal two) with attractive interactions is clearly superior to other previously discussed setups. In sharp contrast to the classical case, we find that the average work output increases with the particle number. The highest overshoot occurs for a small but finite temperature, showing an intricate interplay between thermal and quantum effects. We anticipate that our finding will shed new light on the role of information in controlling thermodynamic fluctuations in the deep quantum regime, which are strongly influenced by quantum correlations in interacting systems.
In this thesis we investigate the work output from an Otto-engine operating simple, fewbody quantum systems under quasi-static driving.We consider 1D systems using the infinite square well as the trapping potential.The aim is to more deeply understand how the working medium of the engine affects the work output, and under which conditions (such as temperatures of the heat reservoirs, particle number etc) a particular working medium is favourable over another.We will first look at how the work output using non-interacting, spin-polarised fermions and bosons differ in the Otto engine.Then, we continue by examining what effect particle number has and how the work output of the non-interacting quantum particles corresponds to that of using a classical, ideal gas as the working medium.After that, a two-body interaction, with a tunable interaction strength is introduced.We will take the interaction to be of the same form as an effective 1D Coulomb interaction for a system under strong cylindrical confinement.We examine how the interacting system compares to the non-interacting one, and what happens when the interaction strength is varied.For the non-interacting case, we find that fermions and bosons can have significantly different work output.The difference will be due to a combination of their respective particle statistics and the monotonically increasing energy level spacings of the infinite square well.Additionally, fermions are seen to be able to have a larger work output than a classical ideal gas, while for bosons, only a system of one or two particles can.Including the two-body interaction, we find that it allows for both fermions and bosons to have a larger work output compared to the non-interacting case.We also see that increasing the interaction strength high enough, fermions and bosons tend to the same work output.
We show that a quantum Szilard engine containing many bosons with attractive interactions enhances the conversion between information and work. Using an ab initio approach to the full quantum-mechanical many-body problem, we find that the average work output increases significantly for a larger number of bosons. The highest overshoot occurs at a finite temperature, demonstrating how thermal and quantum effects conspire to enhance the conversion between information and work. The predicted effects occur over a broad range of interaction strengths and temperatures.
Quantum Szilard engines with an arbitrary number of identical particles are studied in this paper. Analytical expressions for the total work in the low- and high-temperature limits are obtained. The total work depends on both the particle statistics, the odd-even parity, and the temperature of the system. The parity effect is drastic in fermion systems. An odd number of fermions perform work as if they were a single fermion, and an even number of fermions do not perform any work at all. For bosons, there exists a phase transition at a critical temperature under which work done by the engine is always negative. It is found that only above a certain temperature, bosonic quantum Szilard engine does more work than fermionic one. The possible experimental verification of these effects is discussed.
It was recently found that the information-to-work conversion in a quantum Szilard engine can be increased by using a working medium of bosons with attractive interactions. In the original scheme, the work output depends on the insertion and removal position of an impenetrable barrier that acts like a piston, separating the chambers of the engine. Here, we show that the barrier removal process can be made fully reversible, resulting in a full information-to-work conversion if we also allow for the interaction strength to change during the cycle. Hence, it becomes possible to reach the maximum work output per cycle dictated by the second law of thermodynamics. These findings can be experimentally verified, for instance, with ultracold atoms as a working medium, where a change of interaction strength can be controlled by Feshbach resonances.
Abstract In this article, we have realized the quantum Szilard engine (QZE) for non-interacting bosons. We have adopted the Bose–Einstein statistics for this purpose. We have considered fractional power law potential for this purpose and have used the artifact of the quantization of energy. We have calculated the work and the efficiency for non-interacting bosons in fractional power potential. We have shown the dependence of the number of particles for the work and the efficiency. We also have realized the QZE for a single-particle in a Morse potential revealing how the depth of the potential impacts both work and efficiency. Furthermore, we have examined the influence of temperature and the anharmonicity parameter on the work. Finally, we have conducted a comparative analysis, considering both non-interacting bosons in a fractional power law potential and a single-particle in a Morse potential under harmonic approximation conditions.