Quantum Science Colloquium - Adi Pick
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Speaker: Adi Pick, Faculty of Sciences, Applied Physics Department, The Hebrew University of Jerusalem, Israel
Title: Optimal adiabatic protocols for computation with open quantum systems
Abstract:
A major challenge in quantum computation is improving gate fidelities in the presence of realistic noise sources. Two leading approaches for addressing this challenge are adiabatic protocols – based on the principle that slowly varying systems adhere to their instantaneous eigenstates – and quantum optimal control – where ideal controls are found using optimization algorithms. In this talk, I will present our approach for finding optimal adiabatic protocols. By transforming the Hamiltonian into the “inertial frame” of motion, we find protocols which are relatively fast but still robust. In agreement with recent predictions [1, 2], we demonstrate that high fidelity is maintained despite apparent violation of the traditional adiabaticity criterion. We use this approach to demonstrate fast and robust population transfer (STIRAP), geometric logic gates, and state transfer along a one-dimensional atomic chain [3].
While noise in quantum computation is usually an undesired effect, it can sometimes produce interesting theoretical phenomena. For example, open systems (subject to noise) can possess exceptional points, in which the system’s Hamiltonian has less eigenvectors than eigenvalues. In the second part of the talk, I will explain how exceptional points can be used to perform robust asymmetric mode switching in atomic systems [4]. I will present a potential realization of this protocol with NV centers. If time permits, I will conclude the talk with a scheme for boosting the efficiency of photonic Bell measurements using moderate light-matter interaction [5].