Quantum networking holds tremendous promise in transforming computation and communication. Entangled-photon sources are critical for quantum repeaters and networking, while photonic integrated circuits are vital for miniaturization and scalability. In this talk, we focus on generating and manipulating frequency-bin entangled states within integrated platforms. We encode quantum information as a coherent superposition of multiple optical frequencies; this approach is favorable due to its amenability to high-dimensional entanglement and compatibility with fiber transmission. We successfully generate and measure the density matrix of biphoton frequency combs from integrated silicon nitride microrings, fully reconstructing the state in an 8 × 8 two-qudit Hilbert space, the highest so far for frequency bins. Moreover, we employ Vernier electro-optic phase modulation methods to perform time-resolved measurements of biphoton correlation functions. Currently, we are exploring bidirectional pumping of microrings to generate indistinguishable entangled pairs in both directions, aiming to demonstrate key networking operations such as entanglement swapping and Greenberger–Horne–Zeilinger state generation in the frequency domain.
Broadband time-energy entangled photons feature strong temporal correlations with potential for precision delay metrology, but previous work has leveraged only time-of-flight information ultimately limited by the detection jitter and resolution of the time-tagging electronics. Firstly, our work pushes the entanglement-based nonlocal delay metrology from the conventional time-of-flight measurement to a new direction—two-photon interferometry with subpicosecond sensitivity independent of detection resolution. Next, we show the selective sensitivity of frequency-bin encoded Bell states to the sum and difference of biphoton-delays by using a novel reconfigurable setup capable of switching between the Bell states by successively employing single and dual spectral-line pumps.
DWDM with/without super-channel based photonic networks require the use of optical carriers with equalized amplitudes and frequency stabilization of adjacent carriers to realize reliable high bandwidth optical communication systems with high spectral efficiency and long reach. Cascading of electro-optic (EO) modulators is a versatile method for generating tuneable, high repetition rate frequency combs which can be used as sources for the carriers. However, the number of lines produced with this technique is limited by the number of phase modulators. Nonlinear spectral broadening is an attractive option for bandwidth scaling; however, bandwidth scaling of single carrier combs through four wave mixing suffers from unequal comb lines or power limitations due to Brillouin scattering. A simpler technique to increase the number of comb lines would involve using multicarrier excitations for comb generation which would result in a proportional increase in the comb lines. Further, dual-carrier excitation enables an excellent temporal profile for nonlinear spectral broadening. However, since the two carriers have uncorrelated drifts, the resultant frequency combs would be unsuitable for most applications. This issue can be overcome by frequency offset locking the two lasers. Here, we demonstrate frequency offset locking (MHz accuracy) of two diode lasers spaced by 100GHz by using an optical phase locked loop which locks one laser to a RF harmonic of the other. This allows for the generation of frequency comb lines locked to each other even post nonlinear broadening. Using this technique, we demonstrate a 25GHz frequency comb with >90 lines (2THz) in the C-band.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.