Mr. Alejandro Gómez

Alejandro completed his Bachelor and MSc degrees at Universidade de Santiago de Compostela, where he worked on theoretical models of high-temperature superconductors (HTSC). Particularly, on the role of fluctuations in parallel thin-film HTSC, and on the interaction between preformed superconducting pairs and condensed superconducting pairs in LSCO.

While working on his MSc thesis, he developed an interest on quantum technology and quantum information. He joined SQDLab in September 2017 as a visiting academic to undertake research training on superconducting quantum qubits. Alejandro has been awarded a fully funded UQ International Scholarship and proceeded working in SQD Lab as a PhD student.

2020

Karpov D et al, 2020
EPJ B, 93, pp. 49

In a continuous measurement scheme a spin-1/2 particle can be measured and simultaneously driven by an external resonant signal.

Szombati D. et al, 2020
Phys. Rev. Lett, 124, pp. 70401

Quantum mechanics postulates that measuring the qubit's wave function results in its collapse, with the recorded discrete outcome designating the particular eigenstate the qubit collapsed into. We show this picture breaks down when the qubit is strongly driven during measurement. More specifically, for a fast evolving qubit the measurement returns the time-averaged expectation value of the measurement operator, erasing information about the initial state of the qubit, while completely suppressing the measurement back-action. We call this regime `quantum rifling', as the fast spinning of the Bloch vector protects it from deflection into either of its two eigenstates. We study this phenomenon with two superconducting qubits coupled to the same probe field and demonstrate that quantum rifling allows us to measure either one of the two qubits on demand while protecting the state of the other from measurement back-action. Our results allow for the implementation of selective read out multiplexing of several qubits, contributing to efficient scaling up of quantum processors for future quantum technologies.