Abstract: A magneto-encephalography device including a plurality of laser threshold magnetometers for measuring a magnetic field is provided. Each laser threshold magnetometer includes an optical cavity, a laser medium which together with the optical cavity has a laser threshold; a laser pump; and a radio-frequency (RF) drive applied to the laser medium at or around a particular resonance frequency which varies depending on the magnetic field, such that depending on the value of the physical parameter, the RF drive induces transitions between at least two states of the laser medium, each state causing a different laser threshold in an intensity of a laser output, wherein the intensity of the laser output provides a measurement of the magnitude of the magnetic field; wherein the laser threshold magnetometers are configured to be placed on a head of a subject to be monitored.

Abstract: In general, techniques of this disclosure are directed to a sensor for measuring an external magnetic field. The sensor an optical cavity, a laser medium which together with the optical cavity has a laser threshold, a laser pump, and a radio-frequency (RF) drive applied to the laser medium, such that the laser threshold varies with a change in the external magnetic field. The RF drive may be applied to the laser medium at or around a particular resonance frequency which varies depending on the external magnetic field, such that depending on the value of the external magnetic field, the RF drive induces transitions between at least two states of the laser medium, each state causing a different laser threshold in an intensity of a laser output. Further, the intensity of the laser output may provide a measurement of the value of the external magnetic field.

Abstract: A magneto-encephalography device including a plurality of laser threshold magnetometers for measuring a magnetic field is provided. Each laser threshold magnetometer includes an optical cavity, a laser medium which together with the optical cavity has a laser threshold; a laser pump; and a radio-frequency (RF) drive applied to the laser medium at or around a particular resonance frequency which varies depending on the magnetic field, such that depending on the value of the physical parameter, the RF drive induces transitions between at least two states of the laser medium, each state causing a different laser threshold in an intensity of a laser output, wherein the intensity of the laser output provides a measurement of the magnitude of the magnetic field; wherein the laser threshold magnetometers are configured to be placed on a head of a subject to be monitored.

Abstract: In general, techniques of this disclosure are directed to a sensor for measuring an external magnetic field. The sensor an optical cavity, a laser medium which together with the optical cavity has a laser threshold, a laser pump, and a radio-frequency (RF) drive applied to the laser medium, such that the laser threshold varies with a change in the external magnetic field. The RF drive may be applied to the laser medium at or around a particular resonance frequency which varies depending on the external magnetic field, such that depending on the value of the external magnetic field, the RF drive induces transitions between at least two states of the laser medium, each state causing a different laser threshold in an intensity of a laser output. Further, the intensity of the laser output may provide a measurement of the value of the external magnetic field.

Abstract: The correction of errors in the transport and processing of qubits makes use of logical qubits made up of a plurality of physical qubits. The process takes place on a spatial array of physical qubit sites arranged with a quasi-2-dimensional topology having a first line of physical qubit sites and second line of physical qubit sites, where the first and second lines are arranged in parallel, with the sites of the first line in registration with corresponding sites in the second line. Between the first and second lines of physical qubit sites are a plurality of logic function gates, each comprised of a first physical qubit gate site associated with a first physical qubit site in the first line, and a second physical qubit gate site associated with the physical qubit site in the second line that corresponds to the first physical qubit site.

Abstract: A method of fabricating a structure from diamond material or diamond-like carbon material, and a structure according to the method, the method comprising the steps of imposing a structural transformation on the crystallographic structure of the material in a first region located at a first depth below a surface of the material; imposing a structural transformation on the crystallographic structure of the material in a second region located at a second depth below the surface of the material and above of the first region, the second depth being selected so that the first region is separated from the second region by a third region; and removing at least a portion of the material of the first and second regions; wherein the structural transformations are imposed so that the crystallographic structure of the third region is largely unaffected and the third region has opposite surface portions from which material of the first and second regions has been removed.

Abstract: This invention concerns quantum error correction, that is the correction of errors in the transport and processing of qubits, by use of logical qubits made up of a plurality of physical qubits. The process takes place on a spatial array of physical qubit sites arranged with a quasi-2-dimensional topology having a first line of physical qubit sites and second line of physical qubit sites, where the first and second lines are arranged in parallel, with the sites of the first line in registration with corresponding sites in the second line. Between the first and second lines of physical qubit sites are a plurality of logic function gates, each comprised of a first physical qubit gate site associated with a first physical qubit site in the first line, and a second physical qubit gate site associated with the physical qubit site in the second line that corresponds to the first physical qubit site.

Abstract: The present invention provides a photon source comprising an optical waveguide and a material having at least one colour centre. The or each colour centre is arranged for photon emission and the material is grown so that the material is bonded to the optical waveguide and in use at least some of the photons emitted by the or each colour centre are guided in the optical waveguide. The present invention also provides a photon source having an optical waveguide incorporating the material which has the at least one colour centre.

Abstract: This invention concerns quantum computers in which the qubits are closed systems, in that the particle or particles are confined within the structure. A “site” can be produced by any method of confining an electron or other quantum particle, such as a dopant atom, a quantum dot, a cooper pair box, or any combination of these. In particular the invention concerns a closed three-site quantum particle system. The state in the third site is weakly coupled by coherent tunnelling to the first and second states, so that the third state is able to map out the populations of the first and second states as its energy is scanned with respect to the first and second states. In second and third aspects it concerns a readout method for a closed three-state quantum particle system.

Abstract: A method of fabricating a structure in a material.