Open RQC colloquium. Lecture 30

Abstract

Some optical materials having broken inversion symmetry can exhibit a so-called chi(2) nonlinearity which gives rise to important quantum effects including second harmonic generation, sum and difference frequency generation and parametric amplification of light. The superconducting technology enabling extremely low-loss components and Josephson junctions with their inherently nonlinear characteristics makes it possible to engineer various networks (metamaterials) possessing remarkable properties for propagating microwaves. We show that nonlinearity of the superconductor transmission line based on one-dimensional array of inductively-shunted Josephson junctions, the so-called rf-SQUIDs, can be effectively controlled by small perpendicular magnetic field ensuring crossover from typical Kerr-like (centrosymmetric) nonlinearity to the pure chi(2), i.e. non-centrosymmetric nonlinearity. The later property allows excellent phase matching enabling large parametric gain of microwaves in C-band with ultimately quantum-limited performance. First experiments performed with Nb trilayer circuits at temperature T = 4.2 K have confirmed the validity of our concept and shown great promise for operation in the single-photon regime.

Biography

Alexander Zorin graduated from the Physics Department of the Moscow State University in 1976, received the Candidate of Sciences degree in 1981 and worked there as junior scientist and then scientist until 1993. He received the Doctor of Sciences degree from the Moscow State University in 2006. Together with Konstantin Likharev he predicted in 1985 the effect of coherent Bloch oscillations accompanying the single Cooper pair tunneling in small-capacitance Josephson junctions and first proposed the experiment on closing the Quantum Metrology Triangle. These findings played later a crucial role in elaboration of the charge qubits and the quantum standard of current. As a guest professor conducting common research and reading lectures on the Josephson effect and single-electronics, he visited in 1988-1993 several European universities. In 1994 he joined the National Metrology Institute of Germany (PTB, Braunschweig und Berlin) as an expert in single electron tunneling and quantum standard of current. He worked there first as a scientist, a head of Project and a head of Laboratory. Starting from 2007, he is the head of Department “Quantum Electronics” (currently having staff of 25 employees) responsible for research and development of superconducting (nano)circuits. This field includes the Josephson voltage standards, nanoSQUIDs, single electron transistors, Josephson qubits, etc. His special interest is currently focused on nonlinear superconducting circuits and microwave light which obey the laws of quantum mechanics.

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