High fidelity and high efficiency qubit readout scheme

Patent metadata

Field	Value
Publication number	US-9941459-B2
Application number	US-201715495220-A
Country	US
Kind code	B2
Filing date	Apr 24, 2017
Priority date	Sep 28, 2015
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

A technique relates to a qubit readout system. A cavity-qubit system has a qubit and a readout resonator and outputs a readout signal. A lossless superconducting circulator is configured to receive the microwave readout signal from the cavity-qubit system and transmit the microwave readout signal according to a rotation. A quantum limited directional amplifier amplifies the readout signal. A directional coupler is connected to and biases the amplifier to set a working point. A microwave bandpass filter transmits in a microwave frequency band by passing the readout signal while blocking electromagnetic radiation outside of the microwave frequency band. A low-loss infrared filter has a distributed Bragg reflector integrated into a transmission line. The low-loss filter is configured to block infrared electromagnetic radiation while passing the microwave readout signal. The low-loss infrared filter is connected to the microwave bandpass filter to receive input of the microwave readout signal.

First claim

What is claimed is:

1. A method of configuring an apparatus, the method comprising:
providing an outer conductor with a distributed Bragg reflector in the outer conductor; and
providing a center conductor through the distributed Bragg reflector, such that a low-loss filter is formed by the outer conductor, the distributed Bragg reflector, and the center conductor, wherein the center conductor is encircled by material forming the distributed Bragg reflector;
wherein the distributed Bragg reflector comprises a unit cell of at least two different dielectric layers, the unit cell repeats such that one unit cell is formed adjacent to a next unit cell continuously in the redistributed Bragg reflector.

2. The method of claim 1 , wherein the low-loss filter is configured to block infrared electromagnetic radiation while passing a microwave signal;
wherein the center conductor is continuous through a continuous repetition of the unit cell.

3. The method of claim 1 , wherein a repetition of the one unit cell adjacent to the next unit cell is continuous throughout the distributed Bragg reflector without interruption.

4. The method of claim 3 , wherein the unit cell repeats to have a total of N dielectric layers.

5. The method of claim 1 , wherein the distributed Bragg reflector comprises a first dielectric layer and a second dielectric layer adjacent to the first dielectric layer.

6. The method of claim 5 , wherein the first dielectric layer has a first dielectric constant.

7. The method of claim 6 , wherein the second dielectric layer has a second dielectric constant different from the first dielectric constant.

8. The method of claim 1 , wherein the low-loss filter comprises a first connector and a second connector, both connected to opposite ends of the low-loss filter.

9. The method of claim 2 , wherein the low-loss filter is configured to receive the microwave signal as a microwave readout signal.

10. The method of claim 9 , wherein the microwave readout signal includes quantum information.

11. An apparatus comprising:
an outer conductor housing a distributed Bragg reflector in the outer conductor; and
a center conductor through the distributed Bragg reflector, such that a low-loss filter is formed by the outer conductor, the distributed Bragg reflector, and the center conductor, wherein the center conductor is encircled by material forming the distributed Bragg reflector;
wherein the distributed Bragg reflector comprises a unit cell of at least two different dielectric layers, the unit cell repeats such that one unit cell is formed adjacent to a next unit cell continuously in the redistributed Bragg reflector.

12. The apparatus of claim 11 , wherein the low-loss filter is configured to block infrared electromagnetic radiation while passing a microwave signal.

13. The apparatus of claim 11 , wherein a repetition of the one unit cell adjacent to the next unit cell is continuous throughout the distributed Bragg reflector without interruption.

14. The apparatus of claim 13 , wherein the unit cell repeats to have a total of N dielectric layers.

15. The apparatus of claim 11 , wherein the distributed Bragg reflector comprises a first dielectric layer and a second dielectric layer adjacent to the first dielectric layer.

16. The apparatus of claim 15 , wherein the first dielectric layer has a first dielectric constant.

17. The apparatus of claim 16 , wherein the second dielectric layer has a second dielectric constant different from the first dielectric constant.

18. The apparatus of claim 11 , wherein the low-loss filter comprises a first connector and a second connector, both connected to opposite ends of the low-loss filter.

19. The apparatus of claim 12 , wherein the low-loss filter is configured to receive the microwave signal as a microwave readout signal.

20. The apparatus of claim 19 , wherein the microwave readout signal includes quantum information.

Assignees

• IBM

Inventors

• Abdo Baleegh

Classifications

• H10P95/00

  Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass · CPC title

• H01L39/025 Primary

  Electricity · mapped topic

• H01P1/20

  Frequency-selective devices, e.g. filters · CPC title

• H01P3/08

  Microstrips; Strip lines · CPC title

• H01P5/184

  the guides being strip lines or microstrips · CPC title