Examensarbeten för masterexamen // Master Theses
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Browsar Examensarbeten för masterexamen // Master Theses efter Program "Complex adaptive systems (MPCAS), MSc"
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- PostAnalysis of selective photon addition in a bosonic mode with an ancillary qubit(2024) Jirlow, Martin; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap (MC2); Chalmers University of Technology / Department of Microtechnology and Nanoscience (MC2); Johansson, Göran; Abad, TaherehQuantum computation using bosonic modes is a promising alternative to discrete quantum computing with superconducting qubits. Bosonic modes utilize microwave cavities to encode and manipulate quantum information, leveraging the equally spaced energy levels of the cavity to create multi-photon states for robust encoding of quantum information. The dominant source of error in a bosonic mode is singlephoton loss, and finding error correction protocols for this error is an active area of research. Autonomous quantum error correction for a bosonic code was first applied experimentally by Gertler et. al. [J. M. Gertler et al., Nature 590, 243 (2021)], yet they did not reach the break-even point. An alternative protocol for recovering the cavity state after a photon loss is to apply a Selective Number-dependent Arbitrary-Phase Photon-Addition (SNAPPA) gate [M. Kudra et al., arXiv: 2212.12079 (2021)] followed by a quick qubit reset. SNAPPA was implemented experimentally by Kudra et al. yet no accurate theoretical model for this process exists. We derive an accurate and effective Hamiltonian for the SNAPPA gate, and simulate the dynamics to find close agreement with previous experimental results. The derivation highlights a general procedure for finding effective Hamiltonians where current procedures previously have failed.
- PostOn improving the expressive power of chemical computation(2015) Bergh, Erik; Chalmers tekniska högskola / Institutionen för mikroteknologi och nanovetenskap; Chalmers University of Technology / Department of Microtechnology and NanoscienceTraditional CMOS computers are Turing complete information processing systems. They can compute any function that can be described algorithmically. In the past, the computing speed of such systems has been constantly improved. However, for various technological reasons this trends is expected to stop, and alternative ways of computing are under investigation. The computational power of chemical systems has been investigated for quite some time. However, it is not clear what the computing capacity of such systems is. It has been studied how to construct a Turing complete chemical computer in the well-mixed chemical reactor setup. Liekens and Fernando (“Turing complete catalytic computers”, in: Advances in Artificial life, Springer, 2007, pp. 1202-1211) have suggested a systematic way to investigate the chemical completeness issue. Their main finding was that chemical computers are Turing complete in principle. However, spontaneous errors in computation can occur. The frequency of these errors defines the fail rate. In this study, the aim is to understand how the effects of diffusion (e.g. speed of mixing) and the dimensionality of the system influence the fail rate. This is done by performing Monte Carlo simulations. The main conclusions are: The effects of diffusion are indeed extremely important. Finite mixing (low diffusion constant) leads to higher fail rates. It is possible to improve the accuracy of the computer (lower the fail rate) by optimizing the reaction system that implements the chemical computer.