Quantum Simulation with Ultracold Atoms and Trapped Ions.

Quantum Simulation;Ultracold Atoms;Trapped Ions;Quantum Computing;Quantum Information;Physics;Science;Physics

Lin, Guin-DarSteel, Duncan G. ;

University of Michigan

关键词: Quantum Simulation;    Ultracold Atoms;    Trapped Ions;    Quantum Computing;    Quantum Information;    Physics;    Science;    Physics;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/77807/guindarl_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

In this thesis we discuss several aspects of ultracold atomic systems and their applications to quantum simulation. These topics cover a degenerate gas near a Feshbach resonance, superfluids in an optical lattice, trapped-ion quantum computation and simulation.We study a degenerate Fermi gas when the interaction is tuned from the Bose-Einstein Condensation (BEC) side to the Bardeen-Cooper-Schrieffer (BCS) side, investigating effects due to population and mass imbalance. We identify various phases and find that an superfluid shell can be observed within a trap because of the mass mismatch.We study a Fermi gas in a quasi-two-dimensional geometry formed by optical lattices. A two-channel model is proposed to describe the BEC-BCS crossover physics. We find that the higher band excitations are significant and contribute to the closed channel as effective Feshbach ``dressed molecules;;;;. This model predicts a decrease in the cloud size as the interaction is tuned from the BCS side to the BEC side.To investigate superfluidity of bosons in an optical lattice, we calculate the momentum distribution related to the time-of-flight (TOF) interference patterns at finite temperature. We find that a distinct bimodal distribution of the TOF image is presented as long as superfluids emerge, and hence can be used as a reliable signature indicating onset of superfluidity.We propose a large-scale quantum computer architecture by stabilizing a one-dimensional ion chain in a simple linear trap geometry. By arranging ions uniformly through optimizing the anharmonic trap potential, we show that high-fidelity quantum gates can be realized in large ion crystals under the Doppler temperature based on coupling to a near-continuum of transverse motional modes with simple shaped laser pulses.Finally, we demonstrate the trapped ion quantum simulation of the Ising model. Through control of the laser detuning, various coupling networks can be realized. We give a detailed discussion of the frustrated nature in three-ion cases and show achievable phases for larger systems. A comparison of our calculation and experimental data is presented.