Quantum heat engines as quantum computers

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Thermal machines like engines and fridges have been a central point of thermodynamics since its conception 200 years ago. The search for a better understanding of such machines was ultimately linked to the goal of creating better-performing machines with higher power output and efficiency. As thermal machines could be built on increasingly smaller scales, it became clear that they would inevitably reach the microscopic domain of quantum mechanics, and it would no longer suffice to describe them in the language of the (classical) thermodynamics of macroscopic machines. This led to the creation of the new theory of quantum thermodynamics, which tries to combine the two existing theories. In recent years, great theoretical and experimental advancements have been made in the study of quantum thermal machines. Strikingly, nowadays these are no longer just theoretical concepts but are implement in experiments using many different physical platforms like nitrogen-vacancy centers in diamond, NMR setups, ultracold atoms, and ion traps. However, the versatility of quantum thermal machines goes beyond their direct usage as heat engines, refrigerators, or heat pumps. They can be applied in novel ways to create completely new useful devices and serve as a bridge to apply our knowledge of thermal machines to different physical fields.In this spirit, the main goal of this project is to design the very first quantum heat engine which can perform quantum computational algorithms. This will connect quantum thermodynamics to the highly important field of quantum computation. With this new thermodynamic perspective, quantum computers can be much better understood and long-term be optimized, which is an indispensable crucial step for any large-scale application of quantum computers. For this, we have three objectives. First, we begin with a study of quantum heat engines and their fluctuations of efficiency and power if quantum coherences are present in the setup. Based on this we will then develop protocols to implement quantum gates with the strokes of a quantum heat engine. We focus on simple quantum gates, consisting of only one or two qubits which serve as the basic building blocks of any quantum computational algorithm. We will fully study these protocols from a thermodynamic and quantum mechanical perspective and assess their efficiency and fidelity. Lastly, we will elaborate on our engine protocols by making them more realistic by taking into account experiment parameters and scenarios, which can be implemented on current experimental platforms in quantum thermodynamics and quantum computation.