## PhD Proposal: Saurabh Shringarpure

Thursday, April 16, 2020 · 2 PM - 4 PM

Off Campus : via Webex

ADVISOR: Dr. James Franson

TITLE: Quantum Optical State Preparation for Quantum Communication

ABSTRACT: Long-range communication is essentially light-based. The quantum nature of light can be used to encode quantum information and communicate it across vast distances. In this doctoral thesis, we propose to develop new methods of state preparation of light, resource-efficient quantum optical information processing and address the issue of decoherence in quantum optical communications with quantum repeater schemes. We will develop a method that can be used to encode quantum information in the states that typically carry a large number of photons, macroscopic superposition states. We will look at entanglement distribution using a photon number state with linear optical elements like beam splitters and non-linear crystals. Here, the property of the number states that the phase is completely uncertain will be used to generate a state of entangled phases. To analyze the entanglement, we will use a cross-Kerr nonlinearity and show how linear optical elements can be used for a resource-efficient implementation of the nonlinearity. One of the near-term applications of quantum networks is Quantum Key Distribution and next, we will explore a method that will be useful towards this end. Classical pulses undergo dispersion while traveling, but a pair of photons may experience no dispersion if their states are entangled in the frequency. In our work, we will extend the analysis to three or more photons. Finally, we will address the question of decoherence in the context of quantum optical communications. We will work on applying quantum repeater schemes using states generated by splitting number states and also macroscopic superposition states of the kind not limited to the typical Schrodinger cat states.

Proposal will be held using Webex.

TITLE: Quantum Optical State Preparation for Quantum Communication

ABSTRACT: Long-range communication is essentially light-based. The quantum nature of light can be used to encode quantum information and communicate it across vast distances. In this doctoral thesis, we propose to develop new methods of state preparation of light, resource-efficient quantum optical information processing and address the issue of decoherence in quantum optical communications with quantum repeater schemes. We will develop a method that can be used to encode quantum information in the states that typically carry a large number of photons, macroscopic superposition states. We will look at entanglement distribution using a photon number state with linear optical elements like beam splitters and non-linear crystals. Here, the property of the number states that the phase is completely uncertain will be used to generate a state of entangled phases. To analyze the entanglement, we will use a cross-Kerr nonlinearity and show how linear optical elements can be used for a resource-efficient implementation of the nonlinearity. One of the near-term applications of quantum networks is Quantum Key Distribution and next, we will explore a method that will be useful towards this end. Classical pulses undergo dispersion while traveling, but a pair of photons may experience no dispersion if their states are entangled in the frequency. In our work, we will extend the analysis to three or more photons. Finally, we will address the question of decoherence in the context of quantum optical communications. We will work on applying quantum repeater schemes using states generated by splitting number states and also macroscopic superposition states of the kind not limited to the typical Schrodinger cat states.

Proposal will be held using Webex.