Generating a 3D Cluster State via Cold-atom Collisions in an Optical Lattice and Noise Suppression for Field-Sensitive States*

Cluster states, known for their robustness and maximal entanglement, are a potentially important resource in quantum information processing and quantum computing[1][2]. We are working to create a 3D cluster state of atoms in a 3D optical lattice by employing collisional entangling gates [3]. We first prepare a nearly full 3D array of cesium atoms in their vibrational ground states. Subsequent controlled cold collisions then entangle each atom with all of its nearest neighbors. The collisional generation of a 3D cluster state thus entails just three gates, each executed on all the atoms in parallel; the procedure is equivalent to the execution of 3(N³-N²) two-qubit entangling gates, where N³ is the number of atoms in a cubic array. The state-dependent motion that underlies these cold collisions necessitates the transfer of atom qubits into a field-sensitive basis. To preserve qubit coherence, we have developed feedback techniques to stabilize both the optical potential and the magnetic field. We will ultimately characterize the fidelity of our 3D cluster states by measuring their stabilizers, which will use our high-fidelity single atom addressing and state detection techniques.

[1] Raussendorf, R. & Briegel, H. J. Phys. Rev. Lett. 86, 5188–5191 (2001).

[2] Nielsen, Michael A. “Cluster-State Quantum Computation.” Reports on Mathematical Physics 57, no. 1 (2006).

[3] Jaksch, D., Briegel, H.-J., Cirac, J. I., Gardiner, C. W. & Zoller, P. Phys. Rev. Lett. 82, 1975-1978 (1999).