Quantum-state readout using stimulated emissions

Patent metadata

Field	Value
Publication number	US-12411388-B2
Application number	US-202318200531-A
Country	US
Kind code	B2
Filing date	May 22, 2023
Priority date	Dec 1, 2020
Publication date	Sep 9, 2025
Grant date	Sep 9, 2025

Abstract

Quantum-state readout for an atom is performed using stimulated emission, e.g., by illuminating the atoms with electromagnetic radiation (EMR) with wavelengths selected to stimulate photon emission from the atom. Such an emission can be stimulated using four-wave mixing, in this case, three illumination wavelengths are mixed to stimulate the emissions wavelength. The illumination wavelengths are detuned from nearby resonant wavelengths to avoid capture by an atom orbital, which would lead to spontaneous rather than stimulated emission. The stimulated emissions are directional facilitating capture of a strong signal. The illumination wavelengths can be selected to be in different directions from the emissions wavelength to minimize noise in the emissions detection. The net result is a high-signal-to-noise ratio detection signal and quantum-state readout.

First claim

What is claimed is:

1. A method comprising:
illuminating a quantum-state carrier (QSC) with electromagnetic radiation (EMR) comprising a plurality of illumination wavelengths including illumination wavelengths λ 1 , λ 2 and λ 3 , the EMR stimulating the QSC to emit EMR of an emissions wavelength λ 4 , different from each of the illumination wavelengths λ 1 , λ 2 and λ 3 , in the event the QSC was in a first eigenstate during the illuminating;
detecting whether or not EMR of the emissions wavelength λ 4 has been emitted from the QSC; and
determining, based on the detection, whether or not the QSC was in the first eigenstate.

2. The method of claim 1 further comprising before the illuminating, causing the QSC to enter a superposition state, the QSC switching from the superposition state to the eigenstate during the illuminating.

3. The method of claim 1 wherein at least one of the illumination wavelengths is detuned from a resonance wavelength for the QSC.

4. The method of claim 1 wherein a direction of the emissions wavelength λ 4 is different from directions of each of the illumination wavelengths λ 1 , λ 2 and λ 3 .

5. The method of claim 1 wherein the illumination wavelengths λ 1 , λ 2 and λ 3 are each detuned by an amount within the range of 0.1-100 picometers from a respective resonant wavelength for the QSC, and each illumination wavelength λ 1 , λ 2 and λ 3 having a respective illumination direction different from a direction of the emissions EMR, the QSC being an atom, the wavelengths being within a range encompassing near-infrared and visible light.

6. The method of claim 1 wherein the emissions wavelength λ 4 =λ 1 +λ 2 −λ 3 .

7. The method of claim 1 wherein the illumination wavelengths λ 1 , λ 2 and λ 3 are each detuned by an amount within the range of 0.1-100 picometers from a respective resonant wavelength for the QSC.

8. The method of claim 1 wherein the QSC is an atom.

9. A quantum-state readout system comprising:
an illumination system for illuminating a quantum-state carrier (QSC) with electromagnetic radiation (EMR) comprising a plurality of illumination wavelengths including illumination wavelengths λ 1 , λ 2 and λ 3 , the EMR stimulating the QSC to emit EMR of an emissions wavelength λ 4 , different from each of the illumination wavelengths λ 1 , λ 2 and λ 3 , in the event the QSC was in a first eigenstate during the illuminating;
a detector system for detecting whether or not EMR of the emissions wavelength λ 4 has been emitted from the QSC; and
an analyzer for determining, based on the detection, whether or not the QSC was in the first eigenstate.

10. The quantum-state readout system of claim 9 further comprising a quantum-computer for causing the QSC to enter a superposition state, the QSC switching from the superposition state to the first eigenstate during the illuminating.

11. The quantum-state readout system of claim 9 wherein at least one of the wavelengths is detuned from a resonance wavelength for the QSC.

12. The quantum-state readout system of claim 9 wherein a direction of the emissions wavelength λ 4 is different from directions of each of the illumination wavelengths λ 1 , λ 2 and λ 3 .

13. The quantum-state readout system of claim 9 wherein the illumination wavelengths λ 1 , λ 2 and λ 3 are each detuned by an amount within the range of 0.1-100 picometers from a respective resonant wavelength for QSC, and each illumination wavelength λ 1 , λ 2 and λ 3 having a respective illumination direction different from a direction of the emissions EMR, the QSC being an atom, the wavelengths being within a range encompassing near-infrared and visible light.

14. The quantum-state readout system of claim 9 wherein the emissions wavelength λ 4 =λ 1 +λ 2 −λ 3 .

15. The quantum-state readout system of claim 9 wherein the illumination wavelengths λ 1 , λ 2 and λ 3 are each detuned by an amount within the range of 0.1-100 picometers from a respective resonant wavelength for the QSC.

16. The quantum-state readout system of claim 9 wherein the QSC is an atom.

Assignees

• Coldquanta Inc

Inventors

• Radnaev Alexander Georgiyevich

Classifications

• G02F3/02

  Optical bistable devices · CPC title

• G06N10/40

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

• G02F1/3536

  Four-wave interaction · CPC title

• G06N10/70

  Quantum error correction, detection or prevention, e.g. surface codes or magic state distillation · CPC title

• G02F3/00 Primary

  Optical logic elements; Optical bistable devices · CPC title