Inherent polarization entanglement generated from a monolithic semiconductor chip

Abstract

Creating miniature chip scale implementations of optical quantum information protocols is a dream for many in the quantum optics community. This is largely because of the promise of stability and scalability. Here we present a monolithically integratable chip architecture upon which is built a photonic device primitive called a Bragg reflection waveguide (BRW). Implemented in gallium arsenide, we show that, via the process of spontaneous parametric down conversion, the BRW is capable of directly producing polarization entangled photons without additional path difference compensation, spectral filtering or post-selection. After splitting the twin-photons immediately after they emerge from the chip, we perform a variety of correlation tests on the photon pairs and show non-classical behaviour in their polarization. Combined with the BRW's versatile architecture our results signify the BRW design as a serious contender on which to build large scale implementations of optical quantum processing devices.

Electrically Injected Twin Photon Emitting Lasers at Room Temperature

“…In parallel, quantum optics experiments on the photon pairs generated by passive samples based on the same phase-matching technique have allowed us to demonstrate high values of indistinguishability [21,22] and entanglement on polarization [23] and energy-time [22]. The quality of the produced quantum state as well as its compatibility with the telecom network have also allowed to use these sources in multi-user quantum key distribution protocols using standard dense wavelength division multiplexers [24].…”

Generation and manipulation of entangled photons on silicon chips

“…Lv et al [61] generated polarization entanglement by means of the birefringence of a single SWW. Various polarization entanglement sources based on an χ (2) nonlinear waveguide made of (Al)GaAs have also been demonstrated [62][63][64][65][66]; these experiments employing the direct band-gap materials paved the way to the realization of a polarization entanglement source driven by current injection [67,68]. These results show important steps toward the realization of an integrated quantum information system using the polarizations of light.…”

Temporally versatile polarization entanglement from Bragg reflection waveguides

“…Among theses tasks is the preparation and characterization of polarization entanglement that provides some of the strongest evidence of the quantum features of light [1][2][3]. Since the first realizations with parametric down-conversion (PDC) in bulk crystals more than two decades ago [4][5][6], a lot of effort has been put in replacing them both with ferroelectric [7][8][9][10][11] and semiconductor waveguides [12][13][14], which provide higher brightnesses and easier alignment in collinear configurations.In one of such configurations, the cross-polarized PDC photon pairs-called signal and idler-that have at least some nanometers of spectral extent, are divided on a dichroic beam splitter into two paths [15][16][17][18][19]. Due to a strict frequency or energy correlation between signal and idler, a two-partite polarization superposition is created between the output paths of the dichroic mirror.…”

“…Among theses tasks is the preparation and characterization of polarization entanglement that provides some of the strongest evidence of the quantum features of light [1][2][3]. Since the first realizations with parametric down-conversion (PDC) in bulk crystals more than two decades ago [4][5][6], a lot of effort has been put in replacing them both with ferroelectric [7][8][9][10][11] and semiconductor waveguides [12][13][14], which provide higher brightnesses and easier alignment in collinear configurations.…”

“…Due to a strict frequency or energy correlation between signal and idler, a two-partite polarization superposition is created between the output paths of the dichroic mirror. Often, a continuous-wave pump laser is utilized to guarantee tight correlations in the spectral domain [14,20].Bragg-reflection waveguides (BRWs) made of AlGaAs generate indistinguishable photon pairs over several tens of nanometers [14,21] and they have been utilized for narrowband multiplexing of polarization entanglement [22,23]. Due to the very small birefringence between the orthogonally-polarized signal and idler [24], BRWs may work reasonably well in this configuration even without compensating their temporal walk-off.…”