Patents by Inventor Sadamichi Maekawa
Sadamichi Maekawa has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 8437168Abstract: A Josephson quantum computing device and an integrated circuit using Josephson quantum computing devices which can realize a NOT gate operation controlled with 2 bits will be provided. The Josephson quantum computing device (1) comprises: a superconducting ring member (10) having a ?-junction (6) and a 0-junction (7); and a quantum state detecting member (20) constituted by a superconducting quantum interference device arranged outside of the superconducting ring member, wherein a bonding and an antibonding state brought about by a tunneling effect between a |?> and a |?> state as two states degenerate in energy of the superconducting ring member (10) are regarded as quantum bits. The bonding and antibonding states as the quantum bits are read out by the quantum state detecting member (20). The two bit controlled NOT gate operation can be performed by the two quantum bits comprising said quantum bits.Type: GrantFiled: September 7, 2012Date of Patent: May 7, 2013Assignee: Japan Science and Technology AgencyInventors: Sadamichi Maekawa, Taro Yamashita, Saburo Takahashi
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Publication number: 20120326130Abstract: A Josephson quantum computing device and an integrated circuit using Josephson quantum computing devices which can realize a NOT gate operation controlled with 2 bits will be provided. The Josephson quantum computing device (1) comprises: a superconducting ring member (10) having a ?-junction (6) and a 0-junction (7); and a quantum state detecting member (20) constituted by a superconducting quantum interference device arranged outside of the superconducting ring member, wherein a bonding and an antibonding state brought about by a tunneling effect between a | ? > and a | ? > state as two states degenerate in energy of the superconducting ring member (10) are regarded as quantum bits. The bonding and antibonding states as the quantum bits are read out by the quantum state detecting member (20). The two bit controlled NOT gate operation can be performed by the two quantum bits comprising said quantum bits.Type: ApplicationFiled: September 7, 2012Publication date: December 27, 2012Applicant: JAPAN SCIENCE AND TECHNOLOGY AGENCYInventors: Sadamichi MAEKAWA, Taro YAMASHITA, Saburo TAKAHASHI
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Patent number: 8284585Abstract: A Josephson quantum computing device and an integrated circuit using Josephson quantum computing devices which can realize a NOT gate operation controlled with 2 bits will be provided. The Josephson quantum computing device (1) comprises: a superconducting ring member (10) having a ?-junction (6) and a 0-junction (7); and a quantum state detecting member (20) constituted by a superconducting quantum interference device arranged outside of the superconducting ring member, wherein a bonding and an antibonding state brought about by a tunneling effect between a |?> and a |?> state as two states degenerate in energy of the superconducting ring member (10) are regarded as quantum bits. The bonding and antibonding states as the quantum bits are read out by the quantum state detecting member (20). The two bit controlled NOT gate operation can be performed by the two quantum bits comprising said quantum bits.Type: GrantFiled: July 25, 2005Date of Patent: October 9, 2012Assignee: Japan Science and Technology AgencyInventors: Sadamichi Maekawa, Taro Yamashita, Saburo Takahashi
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Publication number: 20120092003Abstract: A magnetic-electric energy conversion device includes: a matrix (12) that includes ferromagnetic particles (10) with conductive properties; an injector (20) that injects carriers into the ferromagnetic particles; and a receptor (22) that accepts the carriers from the ferromagnetic particles. In the magnetic-electric energy conversion device, the carriers tunnel from the injector to the receptor via the ferromagnetic particles, when the magnetization state of the ferromagnetic particles is reversed by magnetic tunneling due to a magnetic field.Type: ApplicationFiled: March 6, 2010Publication date: April 19, 2012Applicants: TOHOKU UNIVERSITY, THE UNIVERSITY OF TOKYOInventors: Masaaki Tanaka, Pham Nam Hai, Shinobu Ohya, Stewart E. Barnes, Sadamichi Maekawa
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Patent number: 7755929Abstract: First and second tunnel junctions having a common electrode composed of a nonmagnetic conductor and each of which has a counterelectrode composed of a ferromagnet are spaced apart from each other by a distance that is shorter than a spin diffusion length of the nonmagnetic conductor. The first tunnel junction injects spin from the ferromagnet into the nonmagnetic conductor and the second tunnel junction detects, between the ferromagnetic metal and the nonmagnetic conductor, a voltage that accompanies spin injection of the first tunnel junction. The nonmagnetic conductor may be a semiconductor or semimetal that is lower in carrier density than a metal. The common electrode alternatively may be composed of a superconductor. A spin injection device thus provided can exhibit a large signal voltage with a low current and under low magnetic field and can be miniaturized in device size.Type: GrantFiled: November 20, 2003Date of Patent: July 13, 2010Assignee: Japan Science and Technology AgencyInventors: Kouichiro Inomata, Sadamichi Maekawa, Saburo Takahashi
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Patent number: 7688623Abstract: The present invention aims to reduce heat fluctuations of a memory cell and thereby provide a stable writing operation when a magnetization reversal process not involving a reversal magnetic field is used for writing into the memory cell. The magnetic memory cell has a structure where first and second magnetization pinned terminals are connected, with a space therebetween, to one surface of a non-magnetic region, and a magnetization free terminal is connected to the other surface. Magnetization directions of the first and second magnetization pinned terminals are anti-parallel to each other. Writing is performed by controlling a polarity of a current flowing between the first and second magnetization pinned terminals through the non-magnetic region and thus reversing magnetization of the magnetization free terminal.Type: GrantFiled: January 8, 2008Date of Patent: March 30, 2010Assignees: Hitachi, Ltd., Tohoku UniversityInventors: Sadamichi Maekawa, Saburo Takahashi, Hiroshi Imamura, Masahiko Ichimura, Hiromasa Takahashi
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Publication number: 20090261319Abstract: A Josephson quantum computing device and an integrated circuit using Josephson quantum computing devices which can realize a NOT gate operation controlled with 2 bits will be provided. The Josephson quantum computing device (1) comprises: a superconducting ring member (10) having a ?-junction (6) and a 0-junction (7); and a quantum state detecting member (20) constituted by a superconducting quantum interference device arranged outside of the superconducting ring member, wherein a bonding and an antibonding state brought about by a tunneling effect between a |?> and a |?> state as two states degenerate in energy of the superconducting ring member (10) are regarded as quantum bits. The bonding and antibonding states as the quantum bits are read out by the quantum state detecting member (20). The two bit controlled NOT gate operation can be performed by the two quantum bits comprising said quantum bits.Type: ApplicationFiled: July 25, 2005Publication date: October 22, 2009Inventors: Sadamichi Maekawa, Taro Yamashita, Saburo Takahshi
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Publication number: 20080175044Abstract: The present invention aims to reduce heat fluctuations of a memory cell and thereby provide a stable writing operation when a magnetization reversal process not involving a reversal magnetic field is used for writing into the memory cell. The magnetic memory cell has a structure where first and second magnetization pinned terminals are connected, with a space therebetween, to one surface of a non-magnetic region, and a magnetization free terminal is connected to the other surface. Magnetization directions of the first and second magnetization pinned terminals are anti-parallel to each other. Writing is performed by controlling a polarity of a current flowing between the first and second magnetization pinned terminals through the non-magnetic region and thus reversing magnetization of the magnetization free terminal.Type: ApplicationFiled: January 8, 2008Publication date: July 24, 2008Inventors: Sadamichi MAEKAWA, Saburo Takahashi, Hiroshi Imamura, Masahiko Ichimura, Hiromasa Takahashi
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Publication number: 20060022220Abstract: A first and a second tunnel junctions (2 and 3) which have a common electrode composed of a nonmagnetic conductor (4) and each of which has a counterelectrode composed of a ferromagnet (6, 8) are disposed spaced apart from each other by a distance that is shorter than a spin diffusion length of the nonmagnetic conductor (4) wherein the first tunnel junction (2) acts to inject spins from the ferromagnet (6) into the nonmagnetic conductor (4) and the second tunnel junction (3) serves to detect, between the ferromagnetic metal (8) and the nonmagnetic conductor (4), a voltage that accompanies spin injection of the first tunnel junction (2) and wherein the nonmagnetic conductor (4) is a nonmagnetic conductor, such as a semiconductor or a semimetal, that is lower in carrier density than a metal. The common electrode alternatively may be composed of a superconductor (4?).Type: ApplicationFiled: November 20, 2003Publication date: February 2, 2006Inventors: Kouichiro Inomata, Sadamichi Maekawa, Saburo Takahashi