Abstract: According to an embodiment, a signal processing apparatus includes a first signal processor, a second signal processor and a third signal processor. The first signal processor suppresses an offset component remaining in a reproduction signal read from an optical recording medium to obtain a first signal. The second signal processor suppresses a nonlinear distortion component remaining in the first signal to obtain a second signal. The third signal processor suppresses a correlation noise component remaining in the second signal to obtain a third signal.

Abstract: According to one embodiment, in an information recording medium including a plurality of data layers, at least one pre-format area is provided on each of the data layers and is circumferentially divided into a plurality of segments. Management information including data layer identification information for identifying the data layers is recorded in at least one of the segments in each of the data layers, using the marks include BCA marks extending radially uniformly. On adjacent ones of the data layers, the BCA marks associated with the management information are recorded in differently positioned segments which are not opposed to each other.

Abstract: According to an embodiment, a quantum communication device includes a receiver, a sift processor, an estimator, first and second storages, a determination unit, an error corrector, a measurement unit, and a privacy amplifier. The sift processor acquires sift processing data by referring to a cryptographic key bit string in a predetermined bit string with a reference basis randomly selected from a plurality of bases. The estimator acquires an estimated error rate by estimating an error rate of the sift processing data from an error rate of part of the sift processing data. When a sift processing data volume stored in the first storage is not smaller than a first threshold, the determination unit determines order of the sift processing data to be corrected based on an estimated error rate, an error rate range that a check matrix can correct, and estimated correction time, and the check matrix used for correction.

Abstract: According to an embodiment, a quantum communication device includes a sift processor, an estimator, a determination unit, and a corrector. The sift processor is configured to acquire sift processing data by referring to a cryptographic key bit string in a predetermined bit string with a reference basis randomly selected from a plurality of bases via a quantum communication channel. The estimator is configured to acquire an estimated error rate of the sift processing data. The determination unit is configured to determine order of the sift processing data in which an error is to be corrected based on the estimated error rate and difference data between a processing speed of error correcting processing and a processing speed of privacy amplification processing. The corrector is configured to acquire one piece of the sift processing data in the order determined by the determination unit, and generate error correcting processing data.

Abstract: According to one embodiment, an information recording and reproducing apparatus including, a focus control module, an objective lens control module, a calculation module, and a tracking control module. If, detection the recording marks line, to focus a laser light of a second wavelength to the recording layer through an objective lens and to operation a recording layer tracking control using a tracking error signal taken out from a second reflected light and a laser light of a first wavelength to a track groove through the objective lens and to operation a guide layer tracking control to control the objective lens using a tracking error signal taken out from a first reflected light.

Abstract: According to an embodiment, in a parity check matrix creation method, all N column vectors in the mask matrix are different. A submatrix having M rows×L columns obtained by arbitrarily extracting L continuous columns from the mask matrix includes B1 first correction rows and Bi ith correction rows. The B1 first correction rows have at least one “1” in total in each of A1 first correction columns. Each of the Bi ith correction rows has at least one “1” in total in Ai-1 (i?1)th correction columns and has “1” in one of Ai ith correction columns included in a column set excluding the first correction columns to (i?1)th correction columns. The Bi ith correction rows include at least one “1” in total in each of the Ai ith correction columns. A sum from A1 to AI equals L.

Abstract: According to an embodiment, a signal processing apparatus includes a first signal processor, a second signal processor and a third signal processor. The first signal processor suppresses an offset component remaining in a reproduction signal read from an optical recording medium to obtain a first signal. The second signal processor suppresses a nonlinear distortion component remaining in the first signal to obtain a second signal. The third signal processor suppresses a correlation noise component remaining in the second signal to obtain a third signal.

Abstract: According to one embodiment, in an information recording medium including a plurality of data layers, at least one pre-format area is provided on each of the data layers and is circumferentially divided into a plurality of segments. Management information including data layer identification information for identifying the data layers is recorded in at least one of the segments in each of the data layers, using the marks include BCA marks extending radially uniformly. On adjacent ones of the data layers, the BCA marks associated with the management information are recorded in differently positioned segments which are not opposed to each other.

Abstract: According to one embodiment, a pickup head includes a plurality of light sources, a first objective lens, second objective lens, a driving unit, a first control unit, a second control unit, light receiving units. The first objective lens focuses a first light beam at a first recording layer. The second objective lens focuses a second light beam at a second recording layer. The driving unit moves the first objective lens and the second objective lens in a first direction and a second direction. The first control unit corrects displacement from target track along the first direction. The second control unit controls a moving direction of a position of the second light spot in the second direction.

Abstract: According to one embodiment, an optical pickup configured to record and to reproduce on a layer of a disk, including, a light source configured to emit a laser beam, an objective lens including a variable use magnification and configured to focus the laser beam on the layer, a collimator lens configured to change the magnification of the objective lens by moving along an optical axis direction, and a liquid crystal module configured to generate spherical aberration to cancel a coma aberration which may occur because an object point and an image point of the objective lens at the use magnification do not exist on an optical axis of the objective lens.

Abstract: A focus servo control device includes a first detector, first controller, second detector, and second controller. The first detector detects a first focus error signal. The first controller controls the objective lens based on the first focus error signal, so that a focal point of the first laser agrees with the guide layer. The second detector detects a second focus error signal. The second controller changes a relative distance between the focal point of the second laser and the focal point of the first laser, so that the focal point of the second laser agrees with a target recording/reproducing layer.

Abstract: According to one embodiment, an information recording medium characterized by including, a first servo layer, a second servo layer, and a data layer, the information recording medium further including, a first spiral track and a second spiral track formed between the first servo layer and the second servo layer and spiraling in opposite directions.

Abstract: According to one embodiment, an optical pickup configured to record and to reproduce on a layer of a disk, including, a light source configured to emit a laser beam, an objective lens including a variable use magnification and configured to focus the laser beam on the layer, a collimator lens configured to change the magnification of the objective lens by moving along an optical axis direction, and a liquid crystal module configured to generate spherical aberration to cancel a coma aberration which may occur because an object point and an image point of the objective lens at the use magnification do not exist on an optical axis of the objective lens.

Abstract: According to one embodiment, an information recording and reproducing apparatus including, a focus control module, an objective lens control module, a calculation module, and a tracking control module. If, detection the recording marks line, to focus a laser light of a second wavelength to the recording layer through an objective lens and to operation a recording layer tracking control using a tracking error signal taken out from a second reflected light and a laser light of a first wavelength to a track groove through the objective lens and to operation a guide layer tracking control to control the objective lens using a tracking error signal taken out from a first reflected light.

Abstract: A focus servo control device includes a first detector, first controller, second detector, and second controller. The first detector detects a first focus error signal. The first controller controls the objective lens based on the first focus error signal, so that a focal point of the first laser agrees with the guide layer. The second detector detects a second focus error signal. The second controller changes a relative distance between the focal point of the second laser and the focal point of the first laser, so that the focal point of the second laser agrees with a target recording/reproducing layer.

Abstract: According to one embodiment, a pickup head includes a plurality of light sources, a first objective lens, second objective lens, a driving unit, a first control unit, a second control unit, light receiving units. The first objective lens focuses a first light beam at a first recording layer. The second objective lens focuses a second light beam at a second recording layer. The driving unit moves the first objective lens and the second objective lens in a first direction and a second direction. The first control unit corrects displacement from target track along the first direction. The second control unit controls a moving direction of a position of the second light spot in the second direction.

Abstract: According to an embodiment of the present invention provides the signal processing system. In the signal processing device that estimates information data from a reception signal by performing iterative processing between a demodulator that demodulates data of n(>m) bits obtained by modulating data of m bits into m bits and an ECC decoder and carrying out maximum a posteriori probability decoding, the device has a module that calculates an a posteriori value after demodulation by performing calculation of modulation data having a pattern estimated to have a high probability alone as modulation data to be decoded from all patterns of the modulation data to be decoded when effecting calculation of the a posteriori value after demodulation based on an a priori value fed back from the ECC decoder at the time of effecting modulation for a second or subsequent time.