Macroscopic Quantum Coherence Team
Team Leader
Jaw-Shen TSAI (Ph.D.)
We are studying macroscopic quantum coherence that occurs in small Josephson junction circuits. In the system, charge and phase degrees of freedoms co-exist, and their coherent control can be exploited as quantum bit (qubit), the basic component of the quantum computer. We have demonstrated such coherence in the superconducting system in 1999, and subsequently pioneered the superconducting solid state qubit technology. So far, we have demonstrated the operation of a 2-qubit-quantum logic gate, first time by a solid-state system. A highly efficient single-shot measurement was also demonstrated. The solid-state system is considered indispensable in realizing the integration required for a practical quantum computer. Recently, we have successfully demonstrated the execution of a small scale quantum protocol by developing a universal set of quantum logic gates with a qubit-coupling switch. Superconducting qubit behaves like an atom and it can be considered as an artificial atom. We are carrying out quantum optics experiments using such artificial atoms.
- Quantum coherence in superconducting circuit
- Quantum bit
- Quantum information processing
- RIKEN Advanced Science Institute Website_Laboratories Page
- Quantum cybernetics Page
- FIRST Quantum Information Processing Project Page
- May 10, 2010
- New quantum optical device with superconductive artificial atoms developed
- January 11, 2008
- Lasing on the spot
Lasing from 'artificial atoms' is demonstrated for the first time
- O.Astafiev. ,A.A.Abdumalikov Jr., A.M.Zagoskin, Yu. A.Paskin,Y.Nakamura and J.S.Tsai:
"Ultimate On-Chip Quantum Amplifier"
Phys. Rev. Lett. 104, 183603(2010) - A.A.Abdumalikov Jr., O.Astafiev. , A.M.Zagoskin, Yu. A.Paskin,Y.Nakamura and J. S.Tsai:
"Electromagnetically induced transparency on a single artificial atom"
Phys. Rev. Lett. 104, 193601(2010) - O.Astafiev. A.M.Zagoskin,A.A.Abdumalikov Jr., Yu. A.Paskin,T.Yamamoto,K.Inomata,Y.Nakamura,J.S.Tsai:
"Resonance Fluorescence of a Single Artificial Atom"
Science, 327, 840 (2010) - Astafiev, O., Inomata, K., Niskanen, A. O., Yamamoto, T., Pashkin, Yu. A., Nakamura, Y. and Tsai, J. S.:
"Single artificial-atom lasing"
Nature, 449, 588 (2007) - Niskanen, A. O., Harrabi, K., Yoshihara, F., Nakamura, Y., Lloyd, S. and Tsai, J. S.:
"Quantum Coherent Tunable Coupling of Superconducting Qubits"
Science, 316, 723 (2007) - Yoshihara, F., Harrabi, K., Niskanen, A. O., Nakamura, Y., and Tsai, J. S.:
"Decoherence of Flux Qubits due to 1/f Flux Noise"
Physical Review Letters, 97, 167001 (2006) - Astafiev, O., Pashkin, Yu. A., Nakamura, Y., Yamamoto, T., and Tsai, J. S.:
"Temperature Square Dependence of the Low Frequency 1/f Charge Noise in the Josephson Junction Qubits"
Physical Review Letters, 96, 137001 (2006) - Astafiev, O., Pashkin, Yu. A., Yamamoto, T., Nakamura, Y., and Tsai, J. S.:
"Quantum Noise in the Josephson Charge Qubit"
Physical Review Letters 93, 267007 (2004). - Yamamoto, T., Pashkin, Yu. A., Astafiev, O., Nakamura, Y., and Tsai, J. S.:
"Demonstration of conditional gate operation using superconducting charge qubits"
Nature 425, 941 (2003). - Pashkin, Yu. A., Yamamoto, T., Astafiev, O., Nakamura, Y., Averin, D. V., and Tsai, J. S.:
"Quantum oscillation in two coupled charge qubit"
Nature 421, 823 (2003).