Hardware-efficient fault-tolerant operations with superconducting circuits

Patent metadata

Field	Value
Publication number	US-11449384-B2
Application number	US-201916959251-A
Country	US
Kind code	B2
Filing date	Jan 5, 2019
Priority date	Jan 5, 2018
Publication date	Sep 20, 2022
Grant date	Sep 20, 2022

Abstract

Techniques for providing hardware-efficient fault-tolerant quantum operations are provided. In some aspects a cavity and an ancilla transmon are used to implement a quantum operation by encoding a logical qubit using more than two energy levels of the cavity, encoding information using more than two energy levels of the ancilla transmon, and creating an interaction between the cavity and the ancilla transmon that decouples at least one error type in the ancilla transmon from the cavity.

First claim

What is claimed is:

1. A method for implementing a fault-tolerant quantum operation using a cavity and an ancilla transmon, the method comprising:
encoding a logical qubit using more than two energy levels of the cavity;
encoding information using more than two energy levels of the ancilla transmon; and
creating an interaction between the cavity and the ancilla transmon that decouples at least one error type in the ancilla transmon from the cavity.

2. The method of claim 1 , wherein creating the interaction between the cavity and the ancilla comprises applying a sideband drive.

3. The method of claim 2 , wherein the evolution of the logical qubit of the cavity is transparent to first-order ancilla errors when the sideband drive is applied.

4. The method of claim 2 , wherein the sideband drive is configured to:
adjust a first frequency shift on the cavity by the ancilla transmon in a first excited state equal to a second frequency shift on the cavity by the ancilla transmon in a second excited state; and
adjust a third frequency shift on the cavity by the ancilla transmon in a ground state excited state is equal to a second frequency shift on the cavity by the ancilla transmon in a second excited state.

5. The method of claim 1 , wherein the quantum operation comprises a quantum logic gate.

6. The method of claim 5 , wherein the quantum logic gate comprises a selective number-dependent arbitrary phase (SNAP) gate.

7. The method of claim 5 , wherein the quantum logic gate comprises a controlled-SWAP gate.

8. The method of claim 5 , wherein the quantum logic gate comprises an exponential-SWAP gate.

9. The method of claim 5 , wherein, when an error occurs in the transmon, the logical qubit of the cavity is unaffected.

10. The method of claim 1 , wherein the quantum operation comprises a quantum measurement.

11. The method of claim 10 , wherein the quantum measurement comprises a quantum parity measurement.

12. The method of claim 10 , wherein the quantum measurement comprises a measurement of an error syndrome.

13. The method of claim 1 , wherein the quantum operation comprises a quantum parity measurement and/or a measurement of an error syndrome.

14. A quantum information system comprising:
a cavity configured to support microwave radiation;
an ancilla transmon dispersively coupled to the cavity;
a microwave source configured to:
apply microwave radiation to the cavity to encode a logical qubit using more than two energy levels of the cavity;
apply microwave radiation to the ancilla transmon to encode information using more than two energy levels of the ancilla transmon; and
apply microwave radiation to create an interaction between the cavity and the ancilla transmon that decouples at least one error type in the ancilla transmon from the cavity.

15. The quantum information system of claim 14 , wherein applying microwave radiation to create an interaction between the cavity and the ancilla transmon comprises applying a sideband drive.

16. The quantum information system of claim 1 , wherein the evolution of the logical qubit of the cavity is transparent to first-order ancilla errors when the sideband drive is applied.

17. The quantum information system of claim 15 , wherein the sideband drive is configured to:
adjust a first frequency shift on the cavity by the ancilla transmon in a first excited state equal to a second frequency shift on the cavity by the ancilla transmon in a second excited state; and
adjust a third frequency shift on the cavity by the ancilla transmon in a ground state excited state is equal to a second frequency shift on the cavity by the ancilla transmon in a second excited state.

18. The quantum information system of claim 14 , wherein the quantum operation comprises a quantum logic gate.

19. The quantum information system of claim 18 , wherein the quantum logic gate comprises a selective number-dependent arbitrary phase (SNAP) gate, a controlled-SWAP gate, or an exponential-SWAP gate.

20. The quantum information system of claim 18 , wherein, when an error occurs in the transmon, the logical qubit of the cavity is unaffected.

Assignees

• Univ Yale

Inventors

• Rosenblum Serge
• Reinhold Philip
• Jiang Liang
• Girvin Steven M
• Frunzio Luigi
• Devoret Michel
• Schoelkopf Iii Robert J

Classifications

• H03K19/003

  Modifications for increasing the reliability {for protection} · CPC title

• B82Y10/00 Primary

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

• H03K19/195

  using superconductive devices · CPC title

• G06F11/1004 Primary

  to protect a block of data words, e.g. CRC or checksum (G06F11/1076 takes precedence; security arrangements for protecting computers or computer systems against unauthorized activity G06F21/00) · CPC title

• G06N10/00

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