RU217971U1 - Low Power Broadband Microwave Superconducting Detector - Google Patents

Abstract

Usage: for registration of ultraweak photon fluxes of the microwave range of wavelengths in systems of integrated quantum optics. The essence of the utility model lies in the fact that a low-power broadband microwave superconducting detector includes a silicon substrate, a contact pad and a waveguide made of Al metal, a sensitive bridge made of a superconducting two-layer TiPt film, which closes the waveguide to the ground. EFFECT: increased detection efficiency, improved signal-to-noise ratio. 3 ill.

Description

The utility model relates to devices for detecting ultraweak microwave photon fluxes in integrated quantum optics systems.

Single photon detectors

According to the results of a patent search conducted by keywords and headings of the IPC in the countries: USA, Russia, China, Japan, the European Community on the websites of the search countries and the patent fund of the Federal Service for Intellectual Property, Patents and Trademarks, the following patents were found.

1. Patent US 20220057261 (published 12/19/2018, G01J-001/44) "Device and method for detecting individual microwave photons" proposes the use of a two-level quantum system. The hit of a photon in such a system will transfer it to an excited state, which is proposed to be monitored.

Despite the fact that a two-level quantum system is capable of distinguishing weak photon fluxes, for fundamental reasons it cannot be used to detect photons in a wide range of microwave wavelengths.

2. Patent US 10210460 (published 10/11/2016, GO6N 99/002) "High-precision threshold detection of single microwave photons using a quantum non-destructive photon detector." The detection system is built around a detector of single microwave photons; the detector is implemented using a Josephson contact, quarter-wave and half-wave resonators.

Despite the fact that the described detector can operate in the single-photon mode, for fundamental reasons it cannot be used to detect photons in a wide range of microwave wavelengths.

3. Patent CN 107091687 B (published on 08.08.2018, G01J-011/00) "Microwave single-photon detector, method of detection and method of obtaining it." The invention describes a superconducting microcircuit, in which the arms of the power splitter are integrated with a Josephson junction. It is proposed to compare the statistics for multiple low-frequency measurements of Josephson junctions.

Despite the fact that the described detector is capable of operating in the single-photon mode, its characteristics are significantly limited for fundamental reasons.

4. Patent US 7049593 (published 28.07.2000, G01J-001/02) "Superconductive Single Photon Detector" proposes the use of a superconducting strip biased near its critical current. When a photon is registered in the visible or infrared wavelength range, the superconducting strip overheats, which is recorded by electronics.

The invention operates in a different frequency range and is not sensitive to the microwave signal.

5. JP 2010109697 (published on 10/30/2008, G01J-001/02) "Microwave photon detector and detection method" proposes the use of a two-level quantum system. Once the two-level system is excited due to the incidence of a microwave photon, the resonator's readout response has continuous changes that are detected by the electronics.

Despite the fact that a two-level quantum system is capable of operating in a single-photon mode, for fundamental reasons it can detect photons in a narrow frequency range, i.e. the system cannot be used to detect photons in a wide range of microwave wavelengths.

6. The closest analogue is described in US patent 9255839 (20.09.2010, G01J-001/44) "Detector of single microwave photons propagating in a waveguide". The invention describes a system consisting of a superconducting waveguide and a normal metal bridge impedance matched to the waveguide and shorting it to a metalized environment. Instead of a normal metal, a semiconductor nanowire, graphene sheet, or carbon nanotube can be used as the material for the bridge. When a microwave photon enters such a system, it will be absorbed by the metal bridge, which will lead to a microscopic increase in temperature in the material; this temperature change is proposed to be monitored. The detector operates at a temperature below the critical temperature of the superconducting waveguide.

The main disadvantage of the closest analogue of the invention is that, due to the topology used in the invention, the detector has a high dark count rate. The high rate of the dark count appears as a result of the detector's own noise - false positives, which are explained by the very principle of the detector's operation. The second disadvantage is the smaller operating frequency band: above 10 GHz.

Figure 1 shows a low power broadband microwave superconducting detector. The device uses a silicon substrate (1). It contains an aluminum pad with a waveguide (2) and a metallized environment (3), titanium (4) - a platinum (5) bridge short-circuits the waveguide to the metallized environment. Instead of titanium, another superconductor with a small superconducting gap can be used; instead of platinum, a noble metal can be used. A contact pad (2) is used to pick up the electrical signal.

To understand the principle of operation of the device, figure 2 shows its top view. Microwave radiation and a test signal are fed into the waveguide (2) and reach the titanium (4) - platinum (5) bridge due to the consistency of the impedance of the bridge and the waveguide. Microwave radiation destroys a countable number of Cooper pairs on the bridge, as a result of which the kinetic inductance of the bridge changes, which is reflected in a change in its impedance, such a change in impedance is measured using a testing signal reflected from the bridge, which has a frequency below the gap of the titanium-platinum bridge.

A cross section of the structure (A-A) is shown in Fig.3. For convenience, in all figures, the same numbers indicate the same elements.

The technical result of the presented utility model, which allows to significantly improve the characteristics of the detector, are:

increase in detection efficiency;

improving the signal-to-noise ratio.

Claims (1)

Low-power broadband microwave superconducting detector, which includes a silicon substrate, a contact pad and a waveguide made of Al metal, a sensitive bridge made of a superconducting two-layer TiPt film, which closes the waveguide to the ground.

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