Raja Marjieh

Light amplification in semiconductor-superconductor structures

We study a new effect of Cooper-pair-based two-photon gain in semiconductor-superconductor structures, showing broadband enhancement of ultrafast two-photon amplification. We further show that with the superconducting enhancement, at moderately high seed intensities, the two-photon gain contribution approaches that of the one-photon gain. A full quantum-optical model of singly- and fully-stimulated two-photon emission is developed. Our results provide new insights on nonlinear light–matter interaction in the superconducting state, including the possibility of coherent control in two-photon semiconductor-superconductor devices. The theoretically-demonstrated effects can have important implications in optoelectronics and in coherent-control applications.

Photonic Bell-state analysis based on semiconductor-superconductor structures

We propose a compact and highly-efficient scheme for complete Bell-state analysis using two-photon absorption in a superconducting proximity region of a semiconductor avalanche photodiode. One-photon transitions to the superconducting Cooper-pair based condensate in the conduction band are forbidden, whereas two-photon transitions are allowed and are strongly enhanced by superconductivity. This Cooper-pair based two-photon absorption results in a strong detection preference of a specified entangled state. Our analysis shows high detection purity of the desired Bell state with negligible false detection probability. The theoretically-demonstrated concept can pave the way towards practical realizations of advanced quantum information schemes.

Linear-optical access to topological insulator surface states

We demonstrate efficient linear-optical access to surface-state spin dynamics in Bi2Se3 by probing transitions between two surface-state Dirac cones, providing a practical technique for spin-current dynamics studies in topological-insulator devices. Using broadband transient-reflectivity pump-probe measurements, we distinguish bulk and surface state-responses, by controlling photon energy and circular polarization at oblique incidence. For pump-photon energies corresponding to bulk-state transitions, the probe polarized co-circularly with the pump shows stronger reflectivity change, compared to the anti-circularly polarized probe. However, pump photon energies corresponding to surface-state transitions result in an opposite effect, with the anti-circularly polarized probe exhibiting stronger reflectivity change. This surprising behavior stems from the surface-state in-plane spin orientation near the Dirac point, and the surface-state spin population remains at the injected energy for several ps. These res...

Semiconductor-superconductor photon beli-state analyzer

The rapidly developing quantum information science relies on the ability to generate and characterize entangled states [1], which are widely realized as photons encoding information in their polarization [2]. Bell state analysis plays a key-role in entanglement characterization yet it requires the use of non-linear effects [3]. Superconducting optoelectronics is an emergent field, focused on light-matter interaction in semiconductor-superconductor structures [4]. Such combinations were shown to result in strongly enhanced quantum and classical nonlinear optical processes, such as highly-efficient entangled-photon pair generation [5], and enhanced two-photon gain [6].

Extreme multiphoton luminescence in GaAs

We demonstrate experimentally extreme multiphoton-absorption cascades in GaAs. We show (2 + 3)- and (2 + 4)-photon luminescence, in which a two-photon transition occurs from the valence to the lower conduction band, followed by another 3- or 4-photon transition to the upper conduction band —inducing luminescence corresponding to several inter-band transitions in GaAs. Our systematic study of the observed effects verifies the cascaded multiphoton absorption, by monitoring the pump intensity and wavelength dependence of the observed luminescence spectra. The measurements are in good agreement with our modeling of multiphoton effects including Auger recombination. Our results open new directions in bulk-material band-structure exploration.

Semiconductor-superconductor two-photon amplifier

We study a new effect of Cooper-pair-based two-photon gain in semiconductor-superconductor structures, showing broadband enhancement of singly- and fully-stimulated ultrafast two-photon gain. These effects can have important implications in optoelectronics and in coherent-control applications.

Two-Photon Amplification In Semiconductor-Superconductor Structures

We study a new effect of Cooper-pair-based two-photon gain in semiconductor-superconductor structures, showing broadband enhancement of singly- and fully-stimulated ultrafast two-photon gain. These effects can have important implications in optoelectronics and in coherent-control applications.