Poolad Imany

Persistent energy–time entanglement covering multiple resonances of an on-chip biphoton frequency comb

We investigate the time-frequency signatures of an on-chip biphoton frequency comb (BFC) generated from a silicon nitride microring resonator. Using a Franson interferometer, we examine the multifrequency nature of the photon pair source in a time entanglement measurement scheme; having multiple frequency modes from the BFC results in a modulation of the interference pattern. This measurement together with a Schmidt mode decomposition shows that the generated continuous variable energy-time entangled state spans multiple pair-wise modes. Additionally, we demonstrate nonlocal dispersion cancellation, a foundational concept in time-energy entanglement, suggesting the potential of the chip-scale BFC for large-alphabet quantum key distribution.

50-GHz-spaced comb of high-dimensional frequency-bin entangled photons from an on-chip silicon nitride microresonator

Quantum frequency combs from chip-scale integrated sources are promising candidates for scalable and robust quantum information processing (QIP). However, to use these quantum combs for frequency domain QIP, demonstration of entanglement in the frequency basis, showing that the entangled photons are in a coherent superposition of multiple frequency bins, is required. We present a verification of qubit and qutrit frequency-bin entanglement using an on-chip quantum frequency comb with 40 mode pairs, through a two-photon interference measurement that is based on electro-optic phase modulation. Our demonstrations provide an important contribution in establishing integrated optical microresonators as a source for high-dimensional frequency-bin encoded quantum computing, as well as dense quantum key distribution.

Characterization of coherent quantum frequency combs using electro-optic phase modulation

We demonstrate a two-photon interference experiment for phase coherent biphoton frequency combs (BFCs), created through spectral amplitude filtering of biphotons with a continuous broadband spectrum. By using an electro-optic phase modulator, we project the BFC lines into sidebands that overlap in frequency. The resulting high-visibility interference patterns provide an approach to verify frequency-bin entanglement even with slow single-photon detectors; we show interference patterns with visibilities that surpass the classical threshold for qubit and qutrit states. Additionally, we show that with entangled qutrits, two-photon interference occurs even with projections onto different final frequency states. Finally, we show the versatility of this scheme for weak-light measurements by performing a series of two-dimensional experiments at different signal-idler frequency offsets to measure the dispersion of a single-mode fiber.

Two-photon interference with frequency-bin entangled photons

We present a novel approach to demonstrate coherence between different bins of a frequency-bin entangled photon-pair. The observed interference patterns provide a simple way to verify frequency-bin entanglement using slow single-photon detectors.

High-speed switching of biphoton delays through electro-optic pump frequency modulation

The realization of high-speed tunable delay control has received significant attention in the scene of classical photonics. In quantum optics, however, such rapid delay control systems for entangled photons have remained undeveloped. Here for the first time, we demonstrate rapid (2.5 MHz) modulation of signal-idler arrival times through electro-optic pump frequency modulation. Our technique applies the quantum phenomenon of nonlocal dispersion cancellation along with pump frequency tuning to control the relative delay between photon pairs. Chirped fiber Bragg gratings are employed to provide large amounts of dispersion which result in biphoton delays exceeding 30 ns. This rapid delay modulation scheme could be useful for on-demand single-photon distribution in addition to quantum versions of pulse position modulation.

Comb-Like Frequency-Bin Entangled Photon Pair Generation in Silicon Nitride Microring Resonators

We report a comb-like frequency-bin entangled photon pair source with a high coincidence to accidental ratio in a silicon nitride microring resonator. We measured a Schmidt number of 4.0, thus verifying high degree of time-frequency entanglement.

Comb-Like Photon Pair Generation in Silicon Nitride Microring Resonators

We report a comb-like photon pair source with a high Coincidence to Accidental Ratio (CAR) in a silicon nitride microring resonator. We are able to generate up to 10 sideband pairs with a free spectral range of 378 GHz.