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Holonomic Quantum Computing. Mikio Nakahara Department of Physics, Kinki University, Japan in collaboration with A. Niskanen, M. Salomaa, S. Tanimura, D. Hayashi, Y. Kondo, Y. Ota, M. Bando. Plan of the talk. 1. What is holonomy (anholonomy)? 2. Wilczek-Zee holonomy
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Holonomic QuantumComputing Mikio Nakahara Department of Physics, Kinki University, Japan in collaboration with A. Niskanen, M. Salomaa, S. Tanimura, D. Hayashi, Y. Kondo, Y. Ota, M. Bando HQC @ Tehran, 4 Jan, 2009
Plan of the talk • 1. What is holonomy (anholonomy)? • 2. Wilczek-Zee holonomy • 3. Isoholonomic Problem • 4. Multi-Partite Construction • 5. Physical Realizations • 5. Summary and Discussions HQC @ Tehran, 4 Jan, 2009
1. What is holonomy?1.1 Holonomy holonomy HQC @ Tehran, 4 Jan, 2009
Holonomy in Mechanics 1 Deformation with Angular Momentum Conserved Shape = Control Manifold HQC @ Tehran, 4 Jan, 2009
Holonomy in Mechanics 2 HQC @ Tehran, 4 Jan, 2009
1.2 Isoholonomic Problem HQC @ Tehran, 4 Jan, 2009
1.3 Holonomic Quantum Computing • Change of Hamiltonian adiabatically along a loop in the control manifold produces the Wilczek-Zee holonomy. Unitary matrices necessary for quantum computing is implemented as holonomies in HQC (Zanardi & Rasetti, 1999). • Timing does not matter. Only the geometrical image of the loop in the control manifold is important. • We are interested in the isoholonomic problem, given a unitary matrix U. HQC @ Tehran, 4 Jan, 2009
Plan of the talk • 1. What is holonomy (anholonomy)? • 2. Wilczek-Zee holonomy • 3. Isoholonomic Problem • 4. Multi-Partite Construction • 5. Physical Realizations • 5. Summary and Discussions HQC @ Tehran, 4 Jan, 2009
2.1 Berry’s Phase HQC @ Tehran, 4 Jan, 2009
Wilczek-Zee Holonomy 1 HQC @ Tehran, 4 Jan, 2009
Wilczek-Zee Holonomy 2 HQC @ Tehran, 4 Jan, 2009
Derivation of WZ holonomy HQC @ Tehran, 4 Jan, 2009
Wilczek-Zee Holonomy 3 HQC @ Tehran, 4 Jan, 2009
Plan of the talk • 1. What is holonomy (anholonomy)? • 2. Wilczek-Zee holonomy • 3. Isoholonomic Problem • 4. Multi-Partite Construction • 5. Physical Realizations • 5. Summary and Discussions HQC @ Tehran, 4 Jan, 2009
3. Isoholonomic Problem HQC @ Tehran, 4 Jan, 2009
Motivation for Studying the Isoholonomic Problem in HQC • Adiabaticity demands that the control parameters be changed as slowly as possible. • On the other hand, operation time should be as short as possible to fight against decoherence. • Therefore we should employ the shortest path in the control parameter space to compromise between two conflicting requirements. HQC @ Tehran, 4 Jan, 2009
3.1 Geometrical Setting HQC @ Tehran, 4 Jan, 2009
3.2Solution of Isoholonomic Problem HQC @ Tehran, 4 Jan, 2009
Solution of Isoholonomic Problem 2 HQC @ Tehran, 4 Jan, 2009
Solution of Isoholonomic Problem 3 HQC @ Tehran, 4 Jan, 2009
Solution of Isoholonomic Problem 4 HQC @ Tehran, 4 Jan, 2009
Inverse Problem HQC @ Tehran, 4 Jan, 2009
Solution to U(g) Isoholonomic Problem HQC @ Tehran, 4 Jan, 2009
3.3 Applications to HQC HQC @ Tehran, 4 Jan, 2009
CNOT gate HQC @ Tehran, 4 Jan, 2009
DFT2 gate HQC @ Tehran, 4 Jan, 2009
Plan of the talk • 1. What is holonomy (anholonomy)? • 2. Wilczek-Zee holonomy • 3. Isoholonomic Problem • 4. Multi-Partite Construction • 5. Physical Realizations • 5. Summary and Discussions HQC @ Tehran, 4 Jan, 2009
4. Multi-Partite Construction • It is not likely to find a quantum system with 2n-fold degenerate ground state. 2100~1030! • Need to find multipartite implementation and make use of entanglement to save computational resources. • A. O. Niskanen, M. Nakahara and M. M. Salomaa, Phys. Rev. A 67, 012319 (2003) HQC @ Tehran, 4 Jan, 2009
4.1 Model Hamiltonian HQC @ Tehran, 4 Jan, 2009
Plan of the talk • 1. What is holonomy (anholonomy)? • 2. Wilczek-Zee holonomy • 3. Isoholonomic Problem • 4. Multi-Partite Construction • 5. Physical Realizations • 5. Summary and Discussions HQC @ Tehran, 4 Jan, 2009
5. Physical Implementations of HQC HQC @ Tehran, 4 Jan, 2009
Example; Isospectral deformation of NMR (Ising) Hamiltonian HQC @ Tehran, 4 Jan, 2009
0 HQC @ Tehran, 4 Jan, 2009
WZ connection HQC @ Tehran, 4 Jan, 2009
Example: Hadamard Gate HQC @ Tehran, 4 Jan, 2009
2-qubit gates HQC @ Tehran, 4 Jan, 2009
Plan of the talk • 1. What is holonomy (anholonomy)? • 2. Wilczek-Zee holonomy • 3. Isoholonomic Problem • 4. Multi-Partite Construction • 5. Physical Realizations • 6. Summary HQC @ Tehran, 4 Jan, 2009
7. Summary HQC @ Tehran, 4 Jan, 2009
Working/studying in my lab. http://alice.math.kindai.ac.jp • Postdoc (April, 2009~ ) salary $ 2,800/month must be younger than 35. • Senior Scientist (April, 2009~ ) salary $2,600/month for 5 working days/week $3,200/month for 6 working days/week must be older than 35. • PhD student, RA salary $13,000/year Tuition fee $10,000/year. (maybe waived) (Almost unlimited research funding for theorists.) HQC @ Tehran, 4 Jan, 2009