EMT/QIS: GaAs hole spins as qubits: Eliminating hyperfine interaction-induced decoherence

点击翻译按钮获取中文摘要

EMT/QIS: GaAs hole spins as qubits: Eliminating hyperfine interaction-induceddecoherenceQuantum Computing is an emerging area of science and engineering. Its broad goalis to harness the superposition of quantum states for computing purposes. The elementarybuilding block of a quantum computer is the quantum bit (qubit). Quantum bits have beendemonstrated in a wide variety of systems ranging from trapped ions, to electron spins insemiconductors, to superconductors. In order to be useful, a qubit must be properlyinitialized, measured, and coupled to other qubits. The quality of a qubit is characterizedby a lifetime (T1) and a coherence time (T2). These time scales vary by several orders ofmagnitude from one system to another (e.g. trapped ion versus superconducting qubits).It is therefore customary to quote a quality factor, Q, which is the ratio of the coherencetime to the typical gate operation time.We will build qubits based on hole spins in GaAs nanometer-size quantum dots.Hole spins are promising candidates since the hole wavefunctions have p-like orbitals. Asa result, hyperfine interactions with the host crystal nuclei are expected to be negligible,leading to spin coherence times approaching the hole spin lifetime of 300 microseconds.Taking into account the typical gate operation time of ~150 ps, a hole spin qubit, ifrealized, could have a quality factor of nearly 2 million, well beyond the threshold forfault tolerance. The primary goal of this project is to accurately measure, and determinewhat limits, the quantum coherence times of hole spins in GaAs quantum dots.