Purdue University Graduate School
NLingaraju_Dissertation_April_2021.pdf (4.18 MB)

Spectral Multiplexing and Information Processing for Quantum Networks

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posted on 2021-04-29, 16:53 authored by Navin Bhartoor LingarajuNavin Bhartoor Lingaraju
Modern fiber-optic networks leverage massive parallelization of communications channels in the spectral domain, as well as low-noise recovery of optical signals, to achieve high rates of information transfer. However, quantum information imposes additional constraints on optical transport networks – the no-cloning theorem forbids use of signal regeneration and many network protocols are premised on operations like Bell state measurements that prize spectral indistinguishability. Consequently, a key challenge for quantum networks is identifying a path to high-rate and high-fidelity quantum state transport.

To bridge this gap between the capabilities of classical and quantum networks, we developed techniques that harness spectral multiplexing of quantum channels, as well as that support frequency encoding. In relation to the former, we demonstrated reconfigurable connectivity over arbitrary subgraphs in a multi-user quantum network. In particular, through flexible provisioning of the pair source bandwidth, we adjusted the rate at which entanglement was distributed over any user-to-user link. To facilitate networking protocols compatible with both spectral multiplexing and frequency encoding, we synthesized a Bell state analyzer based on mixing outcomes that populate different spectral modes, in contrast to conventional approaches that are based on mixing outcomes that populate different spatial paths. This advance breaks the tradeoff between the fidelity of remote entanglement and the spectral distinguishability of photons participating in a joint measurement.

Finally, we take steps toward field deployment by developing photonic integrated circuits to migrate the aforementioned functionality to a chip-scale platform while also achieving the low loss transmission and high-fidelity operation needed for practical quantum networks.


NSF 2034019-ECCS,

AFRL Prime Order No. FA8750-20-P-1705

NSF 1747426-DMR

U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research (Early Career Research Program)

NSF 1839191-ECCS

Army Research Laboratory (W911NF-17-2-0003)


Degree Type

  • Doctor of Philosophy


  • Electrical and Computer Engineering

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Andrew M. Weiner

Additional Committee Member 2

Sunil Bhave

Additional Committee Member 3

Zubin Jacob

Additional Committee Member 4

Minghao Qi