ENTANGLEMENT PROCESS

• US 20130107253A1
• Filed: 10/28/2011
• Published: 05/02/2013
• Est. Priority Date: 10/28/2011
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Kai-Mei Fu
• Inventors: Santori, Charles M., Fu, Kai-Mei, Faraon, Andrei, Beausoleil, Raymond G., Acosta, Victor M., Huang, Zhihong
• Granted Patent: US 8,817,254 B2
• Time in Patent Office: Days
• US Class Current: 356/301
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G01N 21/65 Raman scattering
• CPC Class Codes: G06N 10/00 Quantum computing, i.e. information processing based on quantum-mechanical phenomena

Abstract

A process for entangling quantum states of respective quantum systems measures electromagnetic radiation emitted from a first system and from a second system. The two systems are exposed to excitation radiation having a probability per time of producing a photon, and an interference element is coupled to receive photons from the first and second systems. The process further includes measuring a time during which the first and second systems were exposed to the excitation radiation before a photon is detected on either output channel of the interference element and applying an electromagnetic pulse that causes a relative phase shift of a portion of a quantum state of the first and second systems. Parameters of the electromagnetic pulse are selected based on measurements of the electromagnetic radiation from the first and second systems and the time measured.

Claims

1. A process for entangling quantum states of respective quantum systems comprising:

measuring electromagnetic radiation emitted from a first system;

measuring electromagnetic radiation emitted from a second system;

exposing the first and second systems to excitation radiation having a probability per time of producing a photon from the first and second systems;

coupling an interference element to receive photons from the first system and photons from the second system;

measuring a time during which the first and second systems were exposed to the excitation radiation before a photon is detected on either a first output channel or a second output channel of the interference element; and

applying to one of the first and second systems an electromagnetic pulse that causes a relative phase shift of a portion of a quantum state of the first and second systems, wherein parameters of the electromagnetic pulse are selected based on measurements of the electromagnetic radiation from the first and second systems and the time measured.

2. The process of claim 1, wherein the parameters of the electromagnetic pulse are further selected based on whether the photon is detected on the first or second output channel of the beam splitter.

3. The process of claim 1, wherein measuring the electromagnetic radiation from the first system comprises measuring a first frequency of the electromagnetic radiation emitted from the first system when the first system transitions from an excited state.

4. The process of claim 3, further comprising determining a detuning parameter corresponding to a difference between the first frequency and a second frequency of the excitation radiation.

5. The process of claim 1, wherein the photon detected is a Raman scattered photon from one of the first and second systems.

6. The process of claim 1, wherein exposing the first and second systems to the excitation radiation stops when the photon is detected.

7. The process of claim 1, wherein exposing the first and second systems to the excitation radiation continues after the photon is detected.

8. A system comprising:

first and second qubit devices, each qubit device containing a quantum system having quantum states including a first basis state, a second basis state, and an excited state;

a first measurement system arranged to repeatedly determine respective emission frequencies of the excited states of the quantum systems;

a first excitation system arranged to irradiate the quantum systems with excitations that produce scattered photons;

a second measurement system comprising an interference element coupled to receive scatter photons from the first and second qubit devices, and first and second detectors respectively for first and second output modes of the interference element;

a control system operable to determine a correction needed to transform a combined state of the first and second qubit devices to an entangled state, wherein the control system is to determine the correction using a time at which the second measurement system detects a photon; and

a second excitation system under control of the control system, wherein the control system is to operate the second excitation system to transform the combined state to the entangled state.

9. The system of claim 8, wherein each of the scattered photons is associated with an induced transition between the first basis state and the second basis state of one of the quantum systems.

10. The system of claim 8, wherein the time indicates a duration of the excitations before one of the first and second detectors is to detect a photon.

11. The system of claim 8, wherein in determining the correction, the control system is to use detuning parameters determined using measurements from the first measurement system.

12. The system of claim 8, wherein in determining the correction, the control system is to use an identification of which of the first and second detectors detects the photon.