11 research outputs found
Quantum superposition of three macroscopic states and superconducting qutrit detector
Superconducting quantum coherent circuits have opened up a novel area of
fundamental low-temperature science since they could potentially be the element
base for future quantum computers. Here we report a quasi-three-level coherent
system, the so-called superconducting qutrit, which has some advantages over a
two-level information cell (qubit), and is based on the qutrit readout circuit
intended to measure individually the states of each qubit in a quantum
computer. The designed and implemented radio-frequency superconducting qutrit
detector (rf SQUTRID) with atomic-size ScS-type contact utilizes the
coherent-state superposition in the three-well potential with energy splitting
Delta E_01/k_B=1.5 K at the 30th quantized energy level with good isolation
from the electromagnetic environment. The reason why large values of Delta E_01
(and thus using atomic-size Nb-Nb contact) are required is to ensure an
adiabatic limit for the quantum dynamics of magnetic flux in the rf SQUTRID.Comment: 9 pages, 5 figures, in v.3: text extended, inset in figure 1 (the
device design) adde
Design of deeply cooled ultra-low dissipation amplifier and measuring cell for quantum measurements with a microwave single-photon counter
The requirements and details of designing a measuring cell and
low-back-action deeply-cooled amplifier for quantum measurements at 10 mK are
discussed. This equipment is a part of a microwave single-photon counter based
on a superconducting flux qubit. The high electron mobility transistors (HEMTs)
in the amplifier operate in unsaturated microcurrent regime and dissipate only
1 microwatt of dc power per transistor. Simulated amplifier gain is 15 dB at
450 MHz with a high-impedance (~5 kOhm signal source and standard 50-Ohm
output.Comment: 10 pages, 7 figures. To be published in Fizika Nizkikh Temperatur
(Low Temperature Physics) vol. 50, No.1 (2024
Laser Scanning Microscopy of HTS Films and Devices
The work describes the capabilities of Laser Scanning Microscopy (LSM) as a
spatially resolved method of testing high_Tc materials and devices. The earlier
results obtained by the authors are briefly reviewed. Some novel applications
of the LSM are illustrated, including imaging the HTS responses in rf mode,
probing the superconducting properties of HTS single crystals, development of
twobeam laser scanning microscopy. The existence of the phase slip lines
mechanism of resistivity in HTS materials is proven by LSM imaging.Comment: 17 pages, 21 figures, Submitted to Fizika Nizkikh Temperatur (Low
Temperature Physics