304 research outputs found
Autonomous Calibration of Single Spin Qubit Operations
Fully autonomous precise control of qubits is crucial for quantum information
processing, quantum communication, and quantum sensing applications. It
requires minimal human intervention on the ability to model, to predict and to
anticipate the quantum dynamics [1,2], as well as to precisely control and
calibrate single qubit operations. Here, we demonstrate single qubit autonomous
calibrations via closed-loop optimisations of electron spin quantum operations
in diamond. The operations are examined by quantum state and process
tomographic measurements at room temperature, and their performances against
systematic errors are iteratively rectified by an optimal pulse engineering
algorithm. We achieve an autonomous calibrated fidelity up to 1.00 on a time
scale of minutes for a spin population inversion and up to 0.98 on a time scale
of hours for a Hadamard gate within the experimental error of 2%. These results
manifest a full potential for versatile quantum nanotechnologies.Comment: 9 pages, 5 figure
Controllable Non-Markovianity for a Spin Qubit in Diamond
We present a flexible scheme to realize non-artificial non-Markovian dynamics
of an electronic spin qubit, using a nitrogen-vacancy center in diamond where
the inherent nitrogen spin serves as a regulator of the dynamics. By changing
the population of the nitrogen spin, we show that we can smoothly tune the
non-Markovianity of the electron spin's dynamic. Furthermore, we examine the
decoherence dynamics induced by the spin bath to exclude other sources of
non-Markovianity. The amount of collected measurement data is kept at a minimum
by employing Bayesian data analysis. This allows for a precise quantification
of the parameters involved in the description of the dynamics and a prediction
of so far unobserved data points.Comment: 12 pages, 9 figure, including supplemental materia
- …