An image sensor includes an array of optically switchable magnetic tunnel junctions (MTJs) arranged in columns and rows. The image sensor has first lines of transparent conductive material and second lines of conductive material. Each first line is in contact with the free layers of the MTJs in a corresponding row. Each second line is electrically connected to the fixed layers MTJs in a corresponding column. The first lines are concurrently exposable to radiation. The first and second lines are selectively biasable. In a global reset operation, biasing conditions are such that all MTJs are switched to an anti-parallel state. In a global sense operation, biasing conditions are such that, depending upon the intensity of radiation received at those portions of the first lines in contact with MTJs, the MTJs may switch to a parallel state. In selective read operations, biasing conditions are such that stored data values in the MTJs can be read.

A method for counting photons using a photomultiplier includes obtaining a measurement signal from a raw signal produced by the photomultiplier by correcting the raw signal for a noise signal and/or an offset, wherein an incident photon produces a pulse in the raw signal. The measurement signal is integrated over time to form an analog integrated measurement signal. A number of photons that are incident in the photomultiplier is ascertained by comparing a value of the analog integrated measurement signal to an integral proportionality value which corresponds to a specific number of photons incident in the photomultiplier.

A device includes at least one photoconductor configured for exhibiting an electrical resistance R.sub.photo dependent on an illumination of a light-sensitive region of the at least one photoconductor and at least one photoconductor readout circuit. The photoconductor readout circuit is configured for determining a differential voltage related to changes of the electrical resistance R.sub.photo of the photoconductor. The photoconductor readout circuit includes at least one bias voltage source configured for applying at least one periodically modulated bias voltage to the photoconductor such that the electric output changes its polarity at least once. The device further includes at least one electrical circuit configured to balance the differential voltage at a given illumination level.

An example circuit includes a light detector and a biasing capacitor having (i) a first terminal that applies to the light detector an output voltage that can either bias or debias the light detector and (ii) a second terminal for controlling the output voltage. The circuit includes a first transistor connected to the second terminal of the biasing capacitor and configured to drive the output voltage to a first voltage level above a biasing threshold of the light detector and thereby biasing the light detector. The circuit includes a second transistor connected to the second terminal of the biasing capacitor and configured to drive the output voltage to a second voltage level below the biasing threshold of the light detector and thereby debiasing the light detector. The second voltage is a non-zero voltage that corresponds to a charge level of the biasing capacitor.

A method of resolving a number of photons received by a photon detector includes optically coupling a waveguide to a superconducting wire having alternating narrow and wide portions; electrically coupling the superconducting wire to a current source; and electrically coupling an electrical contact in parallel with the superconducting wire. The electrical contact has a resistance less than a resistance of the superconducting wire while at least one narrow portion of the superconducting wire is in a non-superconducting state. The method includes providing to the superconducting wire, from the current source, a current configured to maintain the superconducting wire in a superconducting state in the absence of incident photons; receiving one or more photons via the waveguide; measuring an electrical property of the superconducting wire, proportional to a number of photons incident on the superconducting wire; and determining the number of received photons based on the electrical property.

An example circuit includes a light detector and a biasing capacitor having (i) a first terminal that applies to the light detector an output voltage that can either bias or debias the light detector and (ii) a second terminal for controlling the output voltage. The circuit includes a first transistor connected to the second terminal of the biasing capacitor and configured to drive the output voltage to a first voltage level above a biasing threshold of the light detector and thereby biasing the light detector. The circuit includes a second transistor connected to the second terminal of the biasing capacitor and configured to drive the output voltage to a second voltage level below the biasing threshold of the light detector and thereby debiasing the light detector. The second voltage is a non-zero voltage that corresponds to a charge level of the biasing capacitor.

A graphene-based broadband radiation sensor and methods for operation thereof are disclosed. The radiation sensor includes an electrical signal path for carrying electrical signals and one or more resonance structures connected to the electrical signal path. Each resonance structure includes a resonator having a resonant frequency. Each resonance structure also includes a graphene junction connected in series with the resonator, the graphene junction including a graphene layer and having an impedance that is dependent on a temperature of the graphene layer. Each resonance structure further includes a heating element that is thermally coupled to the graphene layer and is configured to receive an incident photon, where the temperature of the graphene layer increases in response to the heating element receiving the incident photon.

An infrared detector and an infrared sensor including the infrared detector are provided. The infrared detector includes a plurality of quantum dots spaced apart from each other and including a first component, a first semiconductor layer covering the plurality of quantum dots, and a second semiconductor layer covering the first semiconductor layer.

A receiver according to an embodiment is a terahertz band receiver including an antenna configured to receive a terahertz band signal reflected or transmitted from a measurement target, a detector configured to receive a differential signal including a first input signal V.sub.THz and a second input signal −V.sub.THz with phase difference of 180° to each other from the antenna to detect a voltage, and operate in a concurrent mode, and a buffer amplifier configured to amplify and output a signal detected by the detector.

An electronic device includes a first superconducting wire (with a first end and a second end) having a first threshold superconducting current. The device includes a second superconducting wire (with a first end and a second end) having a second threshold superconducting current that is less than the first threshold superconducting current. The second end of the first superconducting wire and the second end of the second superconducting wire are coupled to a common voltage node. A resistor is coupled between the first superconducting wire and the second superconducting wire, with a first end of the resistor coupled to the first end of the first superconducting wire and a second end of the resistor coupled to the first end of the second superconducting wire. The device includes a current source coupled with the first superconducting wire, and coupled with a combination of the resistor and the second superconducting wire.