Quantum entanglement and quantum computing in the optical frequency comb

Olivier Pfister

Olivier Pfister, Pei J. Wang, Rafael N. Alexander +3 more

Moran Chen, Olivier Pfister

Jing Zhang, Yanfang Wang, Xiaoyu Liu +1 more

Quantum entangled states, especially those having particular properties, are key resources for quantum information and quantum computation. In this paper, we put forward a new scheme to produce 31 continuous–variable (CV) tripartite entanglement fields based on three optical frequency combs via cascade nonlinear processes in an optical parametric cavity, and investigate the spectral characteristics of three frequency combs. The center wavelengths of the three combs are designed as 852 nm, 780 nm (atomic transition lines), and 1550 nm (fiber communication wavelength). The positivity under partial transposition (PPT) criterion, which is sufficient and necessary, is used to evaluate the entanglement in each group of comb lines. This scheme is experimentally feasible and valuable for constructing quantum information networks in future.

Scott A. Diddams

Olivier Pfister

When it comes to practical quantum computing, the two main challenges are circumventing decoherence (devastating quantum errors due to interactions with the environmental bath) and achieving scalability (as many qubits as needed for a real-life, game-changing computation). We show that using, in lieu of qubits, the "qumodes" represented by the resonant fields of the quantum optical frequency comb of an optical parametric oscillator allows one to create bona fide, large scale quantum computing processors, pre-entangled in a cluster state. We detail our recent demonstration of 60-qumode entanglement (out of an estimated 3000) and present an extension to combining this frequency-tagged with time-tagged entanglement, in order to generate an arbitrarily large, universal quantum computing processor.