Massachusetts Institute of Technology

The USA As Represented by the Sec. of the Army

Mikkel Heuck

Dirk Robert Englund

Mihir Pant

Jacob C Mower

Seth Lloyd

Kurt Jacobs

Jelena Notaros

Cosmo Lupo

A two-photon logic gate introduces a phase shift between two photons using a Q-switched cavity with some nonlinearity. The two-photon logic gate catches photons in and releases photons from de-coupled cavity modes in response to electronic or photonic control signals. This 'catch-and-release' two-photon gate can be formed in semiconductor photonic integrated circuit (PIC) that operates at room temperature. When combined with sources, linear circuits, other logic gates, and detectors, it can be used to make a quantum computer with up to 1000 error-corrected logical qubits on a cmPIC, with full qubit connectivity to avoid overhead. Two-qubit gate fidelity exceeding 99% is possible with near-term technology, and scaling beyond 99.9% is possible. Two-photon logic gates are also suitable for gate-based quantum digital computing and for analog quantum computing schemes, such as adiabatic quantum computing or quantum annealing.

Efficient, high-speed two-photon logic gates at room temperature for general-purpose quantum information processing

A photon source to deliver single photons includes a storage ring resonator to receive pump photons and generate a signal photon and an idler photon. An idler resonator is coupled to the storage resonator to couple the idler photon out of the storage resonator and into a detector. Detection of the idler photon stops the pump photons from entering the storage resonator. A signal resonator is coupled to the storage resonator to couple out the signal photon remaining in the storage resonator and delivers the signal photon to applications. The photon source can be fabricated into a photonic integrated circuit to achieve high compactness, reliability, and controllability.

Apparatus and methods for single photon sources

A large-scale tunable-coupling ring array includes an input waveguide coupled to multiple ring resonators, each of which has a distinct resonant wavelength. The collective effect of these multiple ring resonators is to impart a distinct time delay to a distinct wavelength component (or frequency component) in an input signal, thereby carrying out quantum scrambling of the input signal. The scrambled signal is received by a receiver also using a large-scale tunable-coupling ring array. This receiver-end ring resonator array recovers the input signal by imparting a compensatory time delay to each wavelength component. Each ring resonator can be coupled to the input waveguide via a corresponding Mach Zehnder interferometer (MZI). The MZI includes a phase shifter on at least one of its arms to increase the tunability of the ring array.

Apparatus and methods for locked quantum communication using photonic integrated circuits

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Mikkel Heuck