2006/04/18 by M. S. Shahriar, Prabhakar Pradhan, P. Pradhan +4
Chemistry · Computer Science · Physics and Astronomy · #Atom (system on chip) #Atomic physics #Cascade #Chemistry #Cold Atom Physics and Bose-Einstein Condensates #Dipole #Excitation #Excited state #Lamb shift #Laser #Photon #Physics #Quantum #Quantum Information and Cryptography #Quantum mechanics #Quantum optics and atomic interactions #Qubit #Rabi frequency #quant-ph
paper · pdf · doi:10.1016/j.optcom.2007.05.057
6 pages, 5 figures
arxiv created 2006/04/18 · openalex publication_date 2007/06/27 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Current proposals focusing on neutral atoms for quantum computing are mostly based on using single atoms as quantum bits (qubits), while using cavity induced coupling or dipole-dipole interaction for two-qubit operations. An alternative approach is to use atomic ensembles as qubits. However, when an atomic ensemble is excited, by a laser beam matched to a two-level transition (or a Raman transition) for example, it leads to a cascade of many states as more and more photons are absorbed1. In order to make use of an ensemble as a qubit, it is necessary to disrupt this cascade, and restrict the excitation to the absorption (and emission) of a single photon only. Here, we show how this can be achieved by using a new type of blockade mechanism, based on the light-shift imbalance (LSI) in a Raman transition. We describe first a simple example illustrating the concept of light shift imbalanced induced blockade (LSIIB) using a multi-level structure in a single atom, and show verifications of the analytic prediction using numerical simulations. We then extend this model to show how a blockade can be realized by using LSI in the excitation of an ensemble. Specifically, we show how the LSIIB process enables one to treat the ensemble as a two level atom that undergoes fully deterministic Rabi oscillations between two collective quantum states, while suppressing excitations of higher order collective states.