Abstract: A method for using a photon source, which includes a semiconductor structure having a first light emitting diode region, a second region including a quantum dot, a first voltage source, and a second voltage source, is provided. The method includes steps of applying an electric field across said first light emitting diode region to cause light emission by spontaneous emission, wherein the light emitted from said first light emitting diode region is absorbed in said second region and produces carriers to populate said quantum dot; and applying a tuneable electric field across said second region to control the emission energy of said quantum dot, wherein the light emitted from the second region exits said photon source.

Abstract: A method for using a photon source, which includes a semiconductor structure having a first light emitting diode region, a second region including a quantum dot, a first voltage source, and a second voltage source, is provided. The method includes steps of applying an electric field across said first light emitting diode region to cause light emission by spontaneous emission, wherein the light emitted from said first light emitting diode region is absorbed in said second region and produces carriers to populate said quantum dot; and applying a tuneable electric field across said second region to control the emission energy of said quantum dot, wherein the light emitted from the second region exits said photon source.

Abstract: A photon source comprising a quantum structure capable of defining one or more quantum levels such that a photon may be emitted from the quantum structure due to a transition between at least two quantum levels, a control signal configured to vary the transition energy, the transition energy being the energy separation between the at least two quantum levels; and a laser input beam configured to irradiate the quantum structure, the control signal being configured to bring the transition energy into resonance with the laser input beam and out of resonance with the laser input beam, such that the transition energy is resonant with the energy of the laser input beam for a time less than the time to output two photons from the transition.

Abstract: An optoelectronic system comprising a first member and a second member, said first member and said second member comprising a plurality of layers, wherein each member has a profiled mating surface, the first member being connected to the second member such that the growth direction of the layers of the first member are orthogonal to the growth direction of the layers of the second member and the profiled mating surfaces fit together, the first member comprises a waveguide circuit comprising a waveguide and the second member comprises an optoelectronic device with its own optical output which is connected to the waveguide of the first member, the first and second members also being electrically connected.

Abstract: An optical measuring device for measuring a measurement region, the optical device comprising a photonic chip with an interferometer defined on said chip, said interferometer comprising first and second waveguides on said photonic chip and an interference region, wherein the first and second waveguides carry signals from the interference region to the sample region and back to the interference region, the device further comprising a phase adjusting unit configured to vary a phase difference between the signals in the first and second waveguides reflected by the measurement region.

Abstract: An optical system comprising a charged quantum dot having, a charged carrier, first and second ground state levels and a plurality of excited state levels, the first and second ground state energy levels having different spin states such that the said charged carrier cannot transfer between the first and second ground state energy levels without changing its spin state, the system further comprising a controller adapted to control a first radiating beam with energy not more than 100 micro-eV from a first transition within said quantum dot from a first ground state level to a selected excited state level from the plurality of excited state levels to, the system being adapted to enhance the decay rate of a second transition within said quantum dot from the selected excited state level to a second ground state level, but not a first transition, such that a photon is produced due to scattering of a photon from the first radiating beam, wherein the controller is adapted to irradiate the quantum dot with the fir

Abstract: An optoelectronic system comprising a first member and a second member, said first member and said second member comprising a plurality of layers, wherein each member has a profiled mating surface, the first member being connected to the second member such that the growth direction of the layers of the first member are orthogonal to the growth direction of the layers of the second member and the profiled mating surfaces fit together, the first member comprises a waveguide circuit comprising a waveguide and the second member comprises an optoelectronic device with its own optical output which is connected to the waveguide of the first member, the first and second members also being electrically connected.

Abstract: A photon source, comprising: a semiconductor structure, said semiconductor structure comprising: a first light emitting diode region; and a second region comprising a quantum dot; the photon source further comprising: a first voltage source configured to apply an electric field across said first light emitting diode region to cause light emission; a second voltage source configured to apply a tuneable electric field across said second region to control the emission energy of said quantum dot; wherein the semiconductor structure is configured such that light emitted from said first light emitting diode region is absorbed in said second region and produces carriers to populate said quantum dot; and wherein the photon source is configured such that light emitted from the second region exits said photon source.

Abstract: An optical system comprising a charged quantum dot having, a charged carrier, first and second ground state levels and a plurality of excited state levels, the first and second ground state energy levels having different spin states such that the said charged carrier cannot transfer between the first and second ground state energy levels without changing its spin state, the system further comprising a controller adapted to control a first radiating beam with energy not more than 100 micro-eV from a first transition within said quantum dot from a first ground state level to a selected excited state level from the plurality of excited state levels to, the system being adapted to enhance the decay rate of a second transition within said quantum dot from the selected excited state level to a second ground state level, but not a first transition, such that a photon is produced due to scattering of a photon from the first radiating beam, wherein the controller is adapted to irradiate the quantum dot with the fir

Abstract: An optical measuring device for measuring a measurement region, the optical device comprising a photonic chip with an interferometer defined on said chip, said interferometer comprising first and second waveguides on said photonic chip and an interference region, wherein the first and second waveguides carry signals from the interference region to the sample region and back to the interference region, the device further comprising a phase adjusting unit configured to vary a phase difference between the signals in the first and second waveguides reflected by the measurement region.

Abstract: An optical device comprising a quantum dot provided in a resonant confinement structure, an output from said confinement structure and a pulsed excitation source for said quantum dot, wherein the quantum dot is configured to allow the emission of photons having a first energy in response to a pulse from said excitation source, said resonant confinement structure providing optical confinement, the first energy being different to the resonant energy of the resonant confinement structure, the optical device further comprising a timing unit, said timing unit being configured to select photons which have been emitted from the quantum dot due to excitation by a pulse, the timing unit selecting photons emitted after the duration of the pulse which caused the emission of the photons.

Abstract: A photon source comprising a semiconductor heterostructure, said semiconductor heterostructure comprising a quantum well, a barrier region adjacent said quantum well and a quantum dot provided in said quantum well, the photon source further comprising electrical contacts and a power supply coupled to first and second electrical contacts configured to apply a tuneable electric field across said quantum dot to control the emission energy of said quantum dot, said electric field being tuneable across an operating range an wherein the tunneling time of carriers from said quantum dot to said first electrical contact and the tunneling time of carriers from said quantum dot to said second electrical contact are greater than the radiative decay time of an exciton in said quantum dot over said operating range for controlling the emission energy, said photon source being configured such that emission from a single quantum dot exits said photon source.

Abstract: A photon source comprising a quantum structure capable of defining one or more quantum levels such that a photon may be emitted from the quantum structure due to a transition between at least two quantum levels, a control signal configured to vary the transition energy, the transition energy being the energy separation between the at least two quantum levels; and a laser input beam configured to irradiate the quantum structure, the control signal being configured to bring the transition energy into resonance with the laser input beam and out of resonance with the laser input beam, such that the transition energy is resonant with the energy of the laser input beam for a time less than the time to output two photons from the transition.

Abstract: A quantum memory component including a quantum dot molecule having first and second quantum dots provided in respective first and second layers separated by a barrier layer; an exciton comprising an electron and hole bound state in said quantum dot molecule, the spin state of said exciton forming a qubit; first and second electrical contacts respectively provided below the first quantum dot and above the second quantum dot; a voltage source to apply an electric field across said quantum dot molecule; a controller to modulate the electric field across the quantum dot molecule, including an information acquiring circuit to acquire information concerning the relationship between fine structure splitting of the exciton and the applied electric field and a timing circuit to allow switching of the exciton from an indirect configuration to a direct configuration at predetermined times derived from the fine structure splitting.

Abstract: According to one embodiment, a quantum information system includes a source of time dependent entangled photons and an indicating unit. The indicating unit indicates the entangled state of the entangled photons based on the emission time of one or more of the entangled photons.

Abstract: A photon source comprising a photon source body, said photon source body comprising at least one quantum dot; carrier injection means for injecting carriers into said at least one quantum dot and change of state means for changing the state of the carriers within the quantum dot after a predetermined time duration, the carrier injection means injecting carriers which are configured to allow emission of radiation by radiative recombination.

Abstract: An optical system including: a photon source; first directing elements configured to direct photons to follow a first path through the optical system; second directing elements configured to direct photons to follow a second path through the optical system, wherein the second path is the reverse of the first path, photons travelling through the first path having a different polarization to those travelling through the second path; and a mechanism varying the relative phase shift between photons following the first path and photons following the second path.

Abstract: A system for quantum teleportation of a quantum state of an input photon, including: a light emitting diode configured to produce a polarization entangled photon pair; a beam splitter configured to direct photons of the entangled photon pair along respective first and second paths; a measurement unit performing a joint measurement on the input photon; a timing unit configured to measure a first delay between the input photon and the photon of the entangled photon pair at a point of maximum indistinguishability of the photons as they pass through the joint measurement unit, and to measure a second delay between the two photons of the entangled photon pair as they exit the light emitting diode; a controller configured to determine a teleportation measurement is valid if the first delay is within a first predetermined timing window and the second delay is within a second predetermined timing window.

Abstract: An optical device comprising a quantum dot provided in a resonant confinement structure, an output from said confinement structure and a pulsed excitation source for said quantum dot, wherein the quantum dot is configured to allow the emission of photons having a first energy in response to a pulse from said excitation source, said resonant confinement structure providing optical confinement, the first energy being different to the resonant energy of the resonant confinement structure, the optical device further comprising a timing unit, said timing unit being configured to select photons which have been emitted from the quantum dot due to excitation by a pulse, the timing unit selecting photons emitted after the duration of the pulse which caused the emission of the photons.

Abstract: A component comprising a qubit and a controller for said qubit, said component comprising a quantum dot and an excitation portion configured to produce a neutral exciton state in said quantum dot to form said qubit, the component further comprising a measuring unit to make an optical measurement relating to the orientation of said state, wherein said controller comprises voltage source coupled to electrical contacts configured to apply a modulated electric field across said quantum dot, wherein the modulation is faster than the decay time of said neutral exciton state.