Abstract: When a transition control unit stochastically determines whether to accept one of a plurality of state transitions, using a temperature, an energy change, and a random number, depending on a relative relationship between the energy change and thermal excitation energy, the transition control unit adds an offset to the energy change, controls the offset so as to be larger at a local minimum, at which the energy is locally minimized, than at a solution at which the energy is not minimized, and resets the offset to zero when the energy change value is larger than a threshold.

Abstract: When stochastically deciding, based on a change in energy and a random number relating to thermal excitation, whether to accept any of a plurality of state transitions according to the relative relationship between the change in energy and thermal excitation energy, a transition control unit adds an offset to the change in energy, performs control so that the offset at a local minimum where energy is locally minimized is larger than an offset when the energy is not minimized, holds transition information (a transition number) indicating a previous state transition, and prohibits, based on a decoding result for the held transition information, a first state transition out of the present state transition candidates.

Abstract: When a transition control section stochastically determines on the basis of a temperature, an energy change, and a random number whether to allow one of a plurality of state transitions according to a relative relationship between the energy change and a thermal excitation energy, the transition control section adds an offset to the energy change and exercises control so as to set the offset at a local minimum, at which an energy is locally minimized, to be larger than an offset at the time of the energy not being minimized.

Abstract: A stream encryption method encodes plaintext of N number of 1-bit input signal sequences into L (L is N or more) bits of encrypted text using N number of pseudo random sequences and uses only one pseudo random sequence used for the encryption to decode the single corresponding plaintext. This stream encryption method comprises using the N number of pseudo random sequences to divide a L-bit encryption symbol set averagely into two equal parts; selecting either of the two partial sets by a corresponding 1-bit plaintext sequence; and when there are one or more elements of the selected N number of partial sets forming common parts in the sets, using one of those as an encryption symbol.

Abstract: A single-photon generating device is configured to have a solid substrate including abase portion, and a pillar portion which is formed on the surface side of the base portion with a localized level existent in the vicinity of the tip of the base portion. The above pillar portion is formed to have a larger cross section on the base portion side than the cross section on the tip side, so that the light generated from the localized level is reflected on the surface, propagated inside the pillar portion, and output from the back face side of the base portion.

Abstract: A stream encryption method encodes plaintext of N number of 1-bit input, signal sequences into L (L is N or more) bits of encrypted text using N number of pseudo random sequences and uses only one pseudo random sequence used for the encryption to decode the single corresponding plaintext. This stream encryption method comprises using the N number of pseudo random sequences to divide a L-bit encryption symbol set, averagely into two equal parts; selecting either of the two partial sets by a corresponding 1-bit plaintext sequence; and when there are one or more elements of the selected N number of partial sets forming common parts in the sets, using one of those as an encryption symbol.

Abstract: A timing recovery unit detects a phase offset and a frequency offset from a head area of reproduction data and initially corrects them. The timing recovery unit stores data in which a head reproduction signal has been made to be discrete by a fixed clock into a buffer. A phase offset detector detects the phase offset from the data head area in parallel with the operation for writing the data into the buffer. At the same time, a frequency offset detector detects the frequency offset from the data head area in parallel with the operation for writing the data into the buffer. A correction value of the detected phase offset and a correction value of the detected frequency offset are initially set into a digital PLL. While the data is read out from the buffer, a frequency lead-in and a phase lead-in are executed in the head area.

Abstract: A single-photon generator includes an exciton generation part including therein a quantum dot, an excitation part for generating an exciton in the exciton generator part, a recombination control part for controlling recombination timing of the exciton in the exciton generation part, and an optical window provided in the exciton generation part so as to pass a single photon formed as a result of recombination of the exciton, wherein the recombination control part causes, in the exciton generation part, recombination of the excitons at longer intervals than a recombination lifetime of a exciton molecule.

Abstract: A linear filter feeds back an error signal generated using the output of an adaptive filter to a learning circuit. The learning circuit learns the coefficients of the adaptive filter using the error signal. The coefficients of the linear filter are determined depending on the generation method of a target signal for error minimization. In a signal interpolation type timing recovery digital filter, the coefficients of an inverse interpolation filter are determined in such a way as to minimize an error of a signal after interpolation.

Abstract: In a training operation for optimizing a multiplication coefficient for each tap of an FIR equalizer equalizing a read signal read from a recording medium, as a restricted coefficient updating vector applied for updating the multiplication coefficient for each tap of an FIR filter, a vector is utilized which is obtained by projecting, onto a plane perpendicular to a predetermined restricting conditioning vector, a coefficient updating vector determined based on an equalizer error between the output of the FIR equalizer and a reproduction output determined therefrom and a delayed input value for each tap of the FIR equalizer.

Abstract: A single-photon generating device is configured to have a solid substrate including abase portion, and a pillar portion which is formed on the surface side of the base portion with a localized level existent in the vicinity of the tip of the base portion. The above pillar portion is formed to have a larger cross section on the base portion side than the cross section on the tip side, so that the light generated from the localized level is reflected on the surface, propagated inside the pillar portion, and output from the back face side of the base portion.

Abstract: A timing recovery unit detects a phase offset and a frequency offset from a head area of reproduction data and initially corrects them. The timing recovery unit stores data in which a head reproduction signal has been made to be discrete by a fixed clock into a buffer. A phase offset detector detects the phase offset from the data head area in parallel with the operation for writing the data into the buffer. At the same time, a frequency offset detector detects the frequency offset from the data head area in parallel with the operation for writing the data into the buffer. A correction value of the detected phase offset and a correction value of the detected frequency offset are initially set into a digital PLL. While the data is read out from the buffer, a frequency lead-in and a phase lead-in are executed in the head area.

Abstract: A timing recovery unit detects a phase offset and a frequency offset from a head area of reproduction data and initially corrects them. The timing recovery unit stores data in which a head reproduction signal has been made to be discrete by a fixed clock into a buffer. A phase offset detector detects the phase offset from the data head area in parallel with the operation for writing the data into the buffer. At the same time, a frequency offset detector detects the frequency offset from the data head area in parallel with the operation for writing the data into the buffer. A correction value of the detected phase offset and a correction value of the detected frequency offset are initially set into a digital PLL. While the data is read out from the buffer, a frequency lead-in and a phase lead-in are executed in the head area.

Abstract: In a Maximum A posteriori Probability decoding (MAP decoding), a correlation and a deviation of noises for past and future states which depend on input signal patterns in past N bits and future Q bits are calculated by training by a noise correlation arithmetic operating unit 84 and they are stored. Upon reproduction, in a white noise arithmetic operating unit 91, white noise values for the past and future states in which colored noises are converted into white noises are obtained by using the stored correlation and deviation of the noises. In an input signal arithmetic operating unit 92, an input signal (channel information) ?c(yk|Smk) of the MAP decoding is calculated from the white noise values and the deviation for the past and future states. A likelihood in the MAP decoding is obtained from the input signal.

Abstract: In a training operation for optimizing a multiplication coefficient for each tap of an FIR equalizer equalizing a read signal read from a recording medium, as a restricted coefficient updating vector applied for updating the multiplication coefficient for each tap of the FIR filter, a vector is utilized which is obtained by projecting, onto a plane perpendicular to a predetermined restricting conditional vector, a coefficient updating vector determined based on an equalizer error between the output of the FIR equalizer and a reproduction output determined therefrom and a delayed input value for each tap of the FIR equalizer.

Abstract: A single-photon generator includes an exciton generation part including therein a quantum dot, an excitation part for generating an exciton in the exciton generator part, a recombination control part for controlling recombination timing of the exciton in the exciton generation part, and an optical window provided in the exciton generation part so as to pass a single photon formed as a result of recombination of the exciton, wherein the recombination control part causes, in the exciton generation part, recombination of the excitons at longer intervals than a recombination lifetime of a exciton molecule.

Abstract: A linear filter feeds back an error signal generated using the output of an adaptive filter to a learning circuit. The learning circuit learns the coefficients of the adaptive filter using the error signal. The coefficients of the linear filter is determined depending on the generation method of a target signal for error minimization. In a signal interpolation type timing recovery digital filter, the coefficients of an inverse interpolation filter is determined in such a way as to minimize an error of a signal after interpolation.

Abstract: A timing recovery unit detects a phase offset and a frequency offset from a head area of reproduction data and initially corrects them. Therefore, the timing recovery unit stores data in which a head reproduction signal has been made to be discrete by a fixed clock into a buffer. A phase offset detector detects the phase offset from the data head area in parallel with the operation for writing the data into the buffer. At the same time, a frequency offset detector detects the frequency offset from the data head area in parallel with the operation for writing the data into the buffer. A correction value of the detected phase offset and a correction value of the detected frequency offset are initially set into a digital PLL. After that, while the data is read out from the buffer, a frequency lead-in and a phase lead-in are executed in the head area.

Abstract: In a Maximum A posteriori Probability decoding (MAP decoding), a correlation and a deviation of noises for past and future states which depend on input signal patterns in past N bits and future Q bits are calculated by training by a noise correlation arithmetic operating unit 84 and they are stored. Upon reproduction, in a white noise arithmetic operating unit 91, white noise values for the past and future states in which colored noises are converted into white noises are obtained by using the stored correlation and deviation of the noises. In an input signal arithmetic operating unit 92, an input signal (channel information) &Lgr;c(yk|Smk) of the MAP decoding is calculated from the white noise values and the deviation for the past and future states. A likelihood in the MAP decoding is obtained from the input signal.

Abstract: A data conversion processing circuit which effects processing for data conversion which projects two-dimensional data on a plurality of straight lines with different inclinations. The data conversion processing circuit includes a circuit unit for storing two-dimensional data, a circuit unit for producing x and y coordinate locating data, which serves as an addend, according to an angle &thgr; and generating a signal for use in selecting data, a circuit unit for selecting data, which serves as an addend, from among stored data in response to the control signal, and a circuit unit for adding selected data. For producing coordinates and selecting data, the data conversion processing circuit carries out arithmetic operations for a Hough transform expressed as AH(&rgr;, &thgr;)=∫a(&rgr;·cos &thgr;−t·sin &thgr;, &rgr;·sin &thgr;+t·cos &thgr;)dt. For handling different angles &thgr;, the arithmetic operations are carried out in a time-division manner.