Matthew Pysher

Parallel generation of quadripartite cluster entanglement in the optical frequency comb.

Scalability and coherence are two essential requirements for the experimental implementation of quantum information and quantum computing. Here, we report a breakthrough toward scalability: the simultaneous generation of a record 15 quadripartite entangled cluster states over 60 consecutive cavity modes (Q modes), in the optical frequency comb of a single optical parametric oscillator. The amount of observed entanglement was constant over the 60 Q modes, thereby proving the intrinsic scalability of this system. The number of observable Q modes was restricted by technical limitations, and we conservatively estimate the actual number of similar clusters to be at least 3 times larger. This result paves the way to the realization of large entangled states for scalable quantum information and quantum computing.

Entangling the optical frequency comb: Simultaneous generation of multiple 2 × 2 and 2 × 3 continuous-variable cluster states in a single optical parametric oscillator

AbstractWe report on our research effort to generate large-scale multipartite optical-mode entanglement using as few physical resources as possible. We have previously shown that cluster-and GHZ-type N-partite continuous-variable entanglement can be obtained in an optical resonator that contains a suitably designed second-order nonlinear optical medium, pumped by at most

Broadband amplitude squeezing in a periodically poled KTiOPO4 waveguide.

\mathcal{O}

Toward quantum computing with oscillators

(N2) fields. In this paper, we show that the frequency comb of such a resonator can be entangled in an arbitrary number of independent 2 × 2 and 2 × 3 continuousvariable cluster states by a single optical parametric oscillator pumped by just a few optical modes.

Protecting an EPR state by quantum engineering of decoherence

We report the successful design and experimental implementation of three coincident nonlinear interactions, namely ZZZ (type 0), ZYY (type I), and YYZ/YZY (type II) second-harmonic generation of 780 nm light from a 1560 nm pump beam in a single, multigrating, periodically poled KTiOPO(4) crystal. The resulting nonlinear medium is the key component for making a scalable quantum computer over the optical frequency comb of a single optical parametric oscillator.

A new method for locking the signal-field phase difference in a type-II optical parametric oscillator above threshold

We generated -2.2 dB of broadband amplitude squeezing at 1064 nm in a periodically poled KTiOPO4 (PPKTP) waveguide by coupling of the fundamental and second-harmonic cw fields. This is the largest amount of squeezing obtained to date in a KTP waveguide, limited by propagation losses. This result paves the way for further improvements by use of lower-loss buried ion-exchanged waveguides.

Playing the quantum harp: Multipartite squeezing and entanglement of harmonic oscillators

An intrinsically stable type I optical parametric oscillator was built with a periodically poled KTiOPO4 crystal to generate a stable, bright, cw, broadband phase-squeezed beam. A 3.2 dB sensitivity enhancement of optical interferometry was demonstrated on weak electro-optic modulation signals within a 20 MHz squeezing bandwidth. This also realized a channel capacity increase beyond that of coherent optical communication.

Nonlocal restoration of two-mode squeezing in the presence of strong optical loss

Toward the implementation of universal quantum computing in the optical frequency comb, we recently demonstrated the entanglement of 60 cavity modes of a single optical parametric oscillator into 15 independent quadripartite ring cluster states.