Photon source for producing entangled photons
AssigneeKabushiki Kaisha Toshiba
InventorsRichard Mark Stevenson, Andrew James Shields
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Abstract
A photon source comprising: a quantum dot; electrical contacts configured to apply an electric field across said quantum dot: and an electrical source coupled to said contacts, said electrical source being configured to apply a potential such that carriers are supplied to said quantum dot to form a bi-exciton or higher order exciton, wherein said photon source further comprises a barrier configured to increase the time which a carrier takes to tunnel to and from said quantum dot to be greater than the radiative lifetime of an exciton in the quantum dot, the quantum dot being suitable for emission of entangled photons during decay of a bi-exciton or higher order exciton.
Claims19
A photon source comprising:
- a quantum dot;
- electrical contacts configured to apply an electric field across said quantum dot:
- and an electrical source coupled to said contacts, said electrical source being configured to apply a first voltage at which electrons and holes are injected into said quantum dot to form a bi-exciton or higher order exciton, and a second voltage at which injection of electrons and holes is stopped, wherein said photon source further comprises a barrier configured to increase the time which an electron or hole takes to tunnel to or from said quantum dot to be greater than the radiative lifetime of an exciton in the quantum dot when the second voltage is applied, the quantum dot being suitable for emission of entangled pairs of photons during decay of a bi-exciton or higher order exciton.
A method of operating a photon source, said photon source comprising:
- a quantum dot;
- electrical contacts configured to apply an electric field across said quantum dot;
- and an electrical source coupled to said contacts, said electrical source being configured to apply a potential such that electrons and holes are supplied to said quantum dot to form a bi-exciton or higher order exciton, wherein said photon source further comprises a barrier configured to increase the time which an electron or hole takes to tunnel to and from said quantum dot to be greater than the radiative lifetime of an exciton in the quantum dot, the quantum dot being suitable for emission of entangled photons during decay of a bi-exciton or higher order exciton;
- said method comprising:
- switching said electrical source between two voltages, a first voltage being configured to allow injection of electrons and holes into said quantum dot and a second voltage wherein said injection of electrons and holes is stopped and tunneling of electrons and holes to and from the quantum dot is minimised.
A method of fabricating a photon source;
- said method comprising:
- forming an n-type semiconductor region;
- forming a p-type semiconductor region;
- forming a quantum dot in a semiconductor structure between said n and p-type semiconductor regions;
- forming a barrier between said n-type region and said quantum dot,
- providing electrical contacts to said n and p-type semiconductor region,
- said quantum dot being configured such that when a first voltage is applied across said electrical contacts, electrons and hole are injected into said quantum dot and when a second voltage is applied across said electrical contacts, said injection of electrons and holes is stopped,
- said barrier being configured to increase the time which an electron takes to tunnel to or from said quantum dot to be greater than the radiative lifetime of an exciton formed in the quantum dot when said second voltage is applied,
- wherein said quantum dot is configured to be suitable for emission of entangled photons during decay of a bi-exciton or higher order exciton.
Dependencies are inferred from the claim text.