Colin F. McCormick

Strong relative intensity squeezing by four-wave mixing in rubidium vapor

We have measured ¿6.3 dB of relative intensity squeezing at 795 nm, generated by stimulated, nondegenerate four-wave mixing in a hot rubidium vapor. This scheme is of interest for experiments involving cold atoms or atomic ensembles.

Strong Low-Frequency Quantum Correlations From a Four-Wave Mixing Amplifier

Using a simple scheme based on nondegenerate four-wave mixing in a hot vapor, we generate bright twin beams which display a quantum noise reduction in the intensity difference of more than

Ultraslow propagation of matched pulses by four-wave mixing in an atomic vapor

8\phantom{\rule{0.3em}{0ex}}\mathrm{dB}

Fast light, slow light, and phase singularities: a connection to generalized weak values.

. The absence of a cavity makes the system immune to external perturbations, and strong quantum noise reduction is observed at frequencies as low as

Photonic crystal polarizers and polarizing beam splitters

4.5\phantom{\rule{0.3em}{0ex}}\mathrm{kHz}

Experimental demonstration of photonic crystal waveplates

and over a large frequency range.

Demonstration of Superluminal Effects in an Absorptionless, Nonreflective System

We have observed the ultraslow propagation of matched pulses in nondegenerate four-wave mixing in a hot atomic vapor. Probe pulses as short as 70 ns can be delayed by a tunable time of up to 40 ns with little broadening or distortion. During the propagation, a probe pulse is amplified and generates a conjugate pulse which is faster and separates from the probe pulse before getting locked to it at a fixed delay. The precise timing of this process allows us to determine the key coefficients of the susceptibility tensor. The fact that the same configuration has been shown to generate quantum correlations makes this system very promising in the context of quantum information processing.

Microwave measurements of the photonic band gap in a two-dimensional photonic crystal slab

We demonstrate that Aharonov-Albert-Vaidman weak values have a direct relationship with the response function of a system, and have a much wider range of applicability in both the classical and quantum domains than previously thought. Using this idea, we have built an optical system, based on a birefringent photonic crystal, with an infinite number of weak values. In this system, the propagation speed of a polarized light pulse displays both superluminal and slow light behavior with a sharp transition between the two regimes. We show that this systems response possesses two-dimensional, vortex-antivortex phase singularities. Important consequences for optical signal processing are discussed.

Birefringence in two-dimensional bulk photonic crystals applied to the construction of quarter waveplates

We have experimentally demonstrated polarizers and polarizing beam splitters based on microwave-scale two-dimensional photonic crystals. Using polarized microwaves within certain frequency bands, we have observed a squared-sinusoid (Malus) transmission law when using the photonic crystal as a polarizer. The photonic crystal also functions as a polarizing beamsplitter; in this configuration it can be engineered to split incident polarizations in either order and in any direction, making it more versatile than conventional, Brewster-angle beamsplitters.

Experimental observation of superluminal group velocities in bulk two-dimensional photonic bandgap crystals

We have constructed and experimentally tested a microwave half-waveplate using the dispersive birefringent properties of a bulk, two-dimensional, photonic crystal away from its band gap. Our waveplate device exhibited a 200:1 polarization contrast, limited by our experimental resolution. We anticipate that photonic crystal waveplates will have important practical applications in several areas, including integrated photonic circuits.