Physics
Prof. T. S. Mahesh
IISER Pune
Abstract :
Like in ordinary computers, cooling a quantum processor is important to minimize errors. I will describe our recent experiments using a star-topology spin register, wherein the outer ancillary qubits cool the central computation qubit by transferring its entropy to a heat bath with the help of a heatbath algorithmic cooling procedure. Using robust quantum control techniques, we were able to cool the central qubits from room temperature down to 12 K. Exploiting the enhanced polarization of the cold computation qubit, we prepared multiple-quantum coherences of orders up to 15. By benchmarking the decay of these coherences, we investigated the underlying noise process. In another application of a star-like system, we developed a bang-bang optimal quantum control technique to transfer polarization from surrounding 1H spins to a central 13C-13C singlet order, leading to a reduction in the overall singlet-observation time by a factor of 20. Finally, I will describe our recent experimental study of the response of star-topology spin-clusters to an inexact pi-pulse sequence, and show that an Ising coupling between the center and the satellite spins results in robust period-two magnetization oscillations, indicating a temporal ordered phase.<span style="\\"color:" rgb(0,="" 0,="" 0);="" font-family:="" monospace;="" font-size:="" medium;\\"="">
