Deterministic entanglement and tomography of ion-spin qubits

We have implemented a universal quantum logic gate between qubits stored in the spin state of a pair of trapped 40Ca ions. An initial product state was driven to a maximally entangled state deterministically, with 83% fidelity. We present a general approach to quantum state tomography which achieves good robustness to experimental noise and drift, and use it to measure the spin state of the ions. We find the entanglement of formation is 0.54.

[1]  C. S. Wood,et al.  Deterministic Entanglement of Two Trapped Ions , 1998 .

[2]  Boris B. Blinov,et al.  Zero-point cooling and low heating of trapped {sup 111}Cd{sup +} ions , 2004, quant-ph/0404142.

[3]  M. A. Rowe,et al.  Heating of trapped ions from the quantum ground state , 2000 .

[4]  J. P. Home,et al.  Isotope-selective photoionization for calcium ion trapping , 2004 .

[5]  I. Chuang,et al.  Quantum Computation and Quantum Information: Introduction to the Tenth Anniversary Edition , 2010 .

[6]  Andrew G. White,et al.  Measurement of qubits , 2001, quant-ph/0103121.

[7]  A. Steane,et al.  Long-lived mesoscopic entanglement outside the Lamb-Dicke regime. , 2006, Physical review letters.

[8]  X Wang,et al.  Multibit gates for quantum computing. , 2001, Physical review letters.

[9]  Gerard J. Milburn,et al.  Ion Trap Quantum Computing with Warm Ions , 2000 .

[10]  K. Mølmer,et al.  QUANTUM COMPUTATION WITH IONS IN THERMAL MOTION , 1998, quant-ph/9810039.

[11]  Andrew Steane.  How to build a 300 bit, 1 Gop quantum computer , 2004 .

[12]  C. Monroe,et al.  Architecture for a large-scale ion-trap quantum computer , 2002, Nature.

[13]  C. Monroe,et al.  Cooling the Collective Motion of Trapped Ions to Initialize a Quantum Register , 1998, quant-ph/9803023.

[14]  O. Gühne,et al.  03 21 7 2 3 M ar 2 00 6 Scalable multi-particle entanglement of trapped ions , 2006 .

[15]  R. B. Blakestad,et al.  Creation of a six-atom ‘Schrödinger cat’ state , 2005, Nature.

[16]  Ruediger Schack,et al.  Unknown Quantum States and Operations, a Bayesian View , 2004, quant-ph/0404156.

[17]  P. C. Haljan,et al.  Entanglement of trapped-ion clock states , 2005 .

[18]  J. Cirac,et al.  Quantum Computations with Cold Trapped Ions. , 1995, Physical review letters.

[19]  C. Monroe,et al.  Experimental Issues in Coherent Quantum-State Manipulation of Trapped Atomic Ions , 1997, Journal of research of the National Institute of Standards and Technology.

[20]  C. Monroe,et al.  A “Schrödinger Cat” Superposition State of an Atom , 1996, Science.

[21]  D M Lucas,et al.  High-efficiency detection of a single quantum of angular momentum by suppression of optical pumping. , 2004, Physical review letters.

[22]  Hoi-Kwong Lo,et al.  Introduction to Quantum Computation Information , 2002 .

[23]  D. Leibfried,et al.  Experimental demonstration of a robust, high-fidelity geometric two ion-qubit phase gate , 2003, Nature.

[24]  Klaus Molmer,et al.  Entanglement and quantum computation with ions in thermal motion , 2000 .

[25]  F. Schmidt-Kaler,et al.  Realization of the Cirac–Zoller controlled-NOT quantum gate , 2003, Nature.

[26]  P. C. Haljan,et al.  Erratum: Zero-point cooling and low heating of trapped {sup 111}Cd{sup +} ions [Phys. Rev. A 70, 043408 (2004)] , 2006 .

[27]  P. C. Haljan,et al.  04 04 14 2 v 1 2 5 A pr 2 00 4 Zero-Point cooling and low heating of trapped 111 Cd + ions , 2004 .