Sub-nanosecond operations on superconducting quantum register based on Ramsey patterns

Abstract

An ultrafast qubit control concept is proposed and analyzed theoretically to reduce the duration of operations with single and multiple superconducting qubits. It is based on the generation of Ramsey fringes due to unipolar sub-nanosecond control pulses. The key role in the concept is played by the interference of waves of qubit states population propagating forward and backward in time. The influence of the shape and duration of control pulses on the contrast of the interference pattern is revealed in the frame of Ramsey’s paradigm. Protocols for observation of Ramsey oscillations and implementation of various gate operations are developed for flux qubits. We also suggest a notional engineering solution for creating the required sub-nanosecond control pulses with the desired shape and amplitude. It is demonstrated that this makes it possible to control the quantum states of the system with fidelity of more than 99%.

A superconducting adiabatic neuron in a quantum regime

“…. Superconductor technology is a promising platform for such a solution since both superconducting quantum machine learning circuits [16][17][18][19][20][21][22] and superconducting ANNs [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] are rapidly developed nowadays.…”

“…An efficient architecture of a flexible hybrid system requires a close spatial arrangement of the classical ANN with its control quantum co-processor, see Figure 1a . Superconductor technology is a promising platform for such a solution since both superconducting quantum machine learning circuits [ 16 – 22 ] and superconducting ANNs [ 23 – 37 ] are rapidly developed nowadays.…”

Superconducting adiabatic neuron in a quantum regime

“…. Superconductor technology is a promising platform for such a solution since both superconducting quantum machine learning circuits [16][17][18][19][20][21][22] and superconducting ANNs [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] are rapidly developed nowadays.…”

Speeding up qubit control with bipolar single-flux-quantum pulse sequences

“…Due to the wide spectrum of short picosecond SFQ pulse and the small anharmonicity of transmons, the pulse amplitude cannot be large in order to avoid leakage of the qubit state from the computational subspace. In contrast to the flux qubit [35][36][37], in the case of using a simple regular SFQ pulse sequence to control the transmon, the length of the sequence should be sufficiently large. If the pulse repetition rate is synchronized with the transmon qubit frequency, a π/2 rotation with 99.99 % fidelity can be obtained with a regular sequence containing ∼300 pulses [38].…”