Quantum information science exploits quantum mechanical phenomena such as superposition and entanglement to improve classical communication, computation, information processing, and precision measurement. Quantum technology is expected to play a decisive role in enhancing national security and bolstering further scientific discovery. In quantum information processing, single-quantum bit (qubit) operations are not sufficient to unlock all the computational power that is endowed by a collection of qubits. Hence it is necessary and in fact sufficient to add a two-qubit gate such as a controlled-phase gate to a finite set of single-qubit gates to achieve what no longer can be efficiently simulated on a classical computer. In optical quantum computation, photonic qubits are used as information carriers due to their low-noise, long coherence times, light-speed transmission and ease of manipulation at the single-qubit level using standard optical components. To date, only probabilistic two-qubit photonic logic gates based on linear optics and photon detectors have been demonstrated. The implementation, however, is associated with substantial resource overhead and demands stringent technological requirements which are still challenging today. This project addresses the fundamental challenges by developing a deterministic controlled-phase gate to realize the full potential of quantum computation. The educational and outreach activities will train the next-generation quantum scientists and engineers to accelerate the pace of quantum information science and applications.
The goal of this work is to develop a new technological approach to a controlled-phase gate for two photonic qubits using an entirely novel approach based on the generation of photonic dimer states, a chiral nano-photonic waveguide, and a single dipole emitter. The tight optical confinement in the transverse direction in the nanophotonic waveguide allows one to place the dipole emitter at the chiral point and achieve strong coupling between the photon and the emitter such that the scattered photons couple efficiently to the forward but not the backward-propagating mode. The correlated photons form the photonic dimers, which are the bound states of photons and give rise to a non-trivial transmission pi phase shift. The validation of the controlled-phase gate will be achieved using a novel experimental design based on an integrated waveguide approach coupled with number-resolved photon detectors. The demonstration of the photonic dimer state and the corresponding 180-degree phase shift associated with the state with both photons interacting with the dipole emitter will be a major step forward in demonstrating the potential of photonic quantum computing.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
