Techniques of oscillator control for quantum information processing and related systems and methods

Patent metadata

Field	Value
Publication number	US-10540602-B2
Application number	US-201615552998-A
Country	US
Kind code	B2
Filing date	Feb 26, 2016
Priority date	Feb 27, 2015
Publication date	Jan 21, 2020
Grant date	Jan 21, 2020

Abstract

According to some aspects, a method is provided of operating a circuit quantum electrodynamics system that includes a physical qubit dispersively coupled to a quantum mechanical oscillator, the method comprising applying a first electromagnetic pulse to the physical qubit based on a number state of the quantum mechanical oscillator, wherein the first electromagnetic pulse causes a change in state of the quantum mechanical oscillator, and applying, subsequent to application of the first electromagnetic pulse, a second electromagnetic pulse to the quantum mechanical oscillator that coherently adds or removes energy from the quantum mechanical oscillator.

First claim

What is claimed is:

1. A method of operating a circuit quantum electrodynamics system that includes a physical qubit dispersively coupled to a quantum mechanical oscillator, the method comprising:
applying a first electromagnetic pulse to the physical qubit based on a number state of the quantum mechanical oscillator, wherein the first electromagnetic pulse causes a change in state of the quantum mechanical oscillator; and
applying, subsequent to application of the first electromagnetic pulse, a second electromagnetic pulse to the quantum mechanical oscillator that coherently adds or removes energy from the quantum mechanical oscillator.

2. The method of claim 1 , further comprising:
driving the physical qubit to a ground state prior to application of the first electromagnetic pulse; and
driving the physical qubit to the ground state after application of the first electromagnetic pulse.

3. The method of claim 1 , further comprising measuring a parity of the quantum mechanical oscillator by applying a third electromagnetic pulse to the physical qubit based on the number state of the quantum mechanical oscillator.

4. The method of claim 1 , further comprising measuring the number state of the quantum mechanical oscillator by applying a fourth electromagnetic pulse to the physical qubit.

5. The method of claim 1 , wherein a frequency of the first electromagnetic pulse is based on the number state of the quantum mechanical oscillator.

6. The method of claim 1 , wherein an amplitude of the first electromagnetic pulse is less than a magnitude of a dispersive coupling between the physical qubit and the quantum mechanical oscillator.

7. The method of claim 1 , wherein the change in state of the quantum mechanical oscillator caused by the first electromagnetic pulse is a quantum phase change of one or more Fock state components of the quantum mechanical oscillator.

8. The method of claim 1 , wherein a qubit frequency shift per photon in the quantum mechanical oscillator is larger than a qubit transition line width.

9. The method of claim 1 , wherein the first electromagnetic pulse includes a first frequency component and wherein the quantum mechanical oscillator is resonant at a second frequency, different from the first frequency.

10. The method of claim 1 , wherein a frequency of the second electromagnetic pulse is a resonant frequency of the quantum mechanical oscillator.

11. The method of claim 1 , wherein the second electromagnetic pulse is based at least in part on the first electromagnetic pulse.

12. The method of claim 1 , wherein the physical qubit comprises a Josephson junction.

13. The method of claim 12 , wherein the physical qubit is a superconducting transmon qubit.

14. The method of claim 1 , wherein the quantum mechanical oscillator is a radiation cavity.

15. The method of claim 14 , wherein the quantum mechanical oscillator is a microwave stripline cavity.

16. The method of claim 1 , wherein the first electromagnetic pulse comprises microwave frequencies.

17. A circuit quantum electrodynamics system, comprising:
a physical qubit;
a quantum mechanical oscillator dispersively coupled to the physical qubit; and
at least one electromagnetic radiation source configured to independently apply electromagnetic pulses to the qubit and to the oscillator by:
applying a first electromagnetic pulse to the physical qubit based on a number state of the quantum mechanical oscillator to cause a change in state of the quantum mechanical oscillator; and
applying a second electromagnetic pulse to the quantum mechanical oscillator to coherently add or remove energy from the quantum mechanical oscillator.

18. The system of claim 17 , wherein:
the quantum mechanical oscillator is a first quantum mechanical oscillator;
the system further comprises a second quantum mechanical oscillator coupled to the physical qubit; and
a quality factor of the second quantum mechanical oscillator is lower than a quality factor of the first quantum mechanical oscillator.

19. The system of claim 17 , wherein the change in state of the quantum mechanical oscillator caused by the first electromagnetic pulse is a quantum phase change of one or more Fock state components of the quantum mechanical oscillator.

20. The system of claim 17 , wherein a qubit frequency shift per photon in the quantum mechanical oscillator is larger than a qubit transition line width.

21. The system of claim 17 , wherein the first electromagnetic pulse includes a first frequency component and wherein the quantum mechanical oscillator is resonant at a second frequency, different from the first frequency.

22. The system of claim 17 , wherein the physical qubit comprises a Josephson junction.

23. The system of claim 22 , wherein the physical qubit is a superconducting transmon qubit.

24. The system of claim 17 , wherein the quantum mechanical oscillator is a radiation cavity.

25. The system of claim 24 , wherein the quantum mechanical oscillator is a microwave stripline cavity.

26. The system of claim 17 , wherein the first electromagnetic pulse is configured to comprise microwave frequencies.

Assignees

• Univ Yale

Inventors

• Heeres Reinier
• Vlastakis Brian
• Albert Victor V
• Krastanov Stefan
• Jiang Liang
• Schoelkopf Iii Robert J

Classifications

• H03K19/195

  using superconductive devices · CPC title

• H03B5/1847

  the active element in the amplifier being a semiconductor device · CPC title

• G06N10/00 Primary

  Quantum computing, i.e. information processing based on quantum-mechanical phenomena · CPC title

• G06N10/40 Primary

  Physical realisations or architectures of quantum processors or components for manipulating qubits, e.g. qubit coupling or qubit control · CPC title

• B82Y10/00

  Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic · CPC title