Purdue University Graduate School
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posted on 2020-12-09, 17:51 authored by Hsuan-Hao LuHsuan-Hao Lu
Encoding quantum information in narrow, equispaced frequency bins has emerged as a novel scheme for photonic quantum information processing (QIP) due to its inherent high-dimensionality and compatibility with dense spectral multiplexing networks. Generation and distribution of such state, commonly known as biphoton frequency combs (BFCs), have been widely demonstrated over fiber- and chip-compatible platforms, while the processing side is relatively underdeveloped. In this dissertation, we focus on the realization of the quantum frequency processor, a photonic device comprised of an alternating sequence of electro-optic phase modulators and Fourier-transform pulse shapers, capable of processing BFCs in a parallel and low-noise fashion. Utilizing standard telecommunication components, we experimentally complete the universal gate set required for scalable quantum computing, including a high-fidelity Hadamard gate and a coincidence-basis controlled-NOT gate. High-dimensional quantum operations are also explored on our device, where we implement the first frequency-bin tritter, a three-mode extension of the Hadamard gate. Moreover, we exploit the natural parallelizability of the system and implement tunable and independent qubit operations on co-propagating qubits. We realize frequency-bin Hong-Ou-Mandel interference with record-high visibility, as well as the first high-fidelity spectral correlation flip on two-qubit entangled states. Finally, we demonstrate essential functionalities for quantum networking, including arbitrary single-qubit rotations, and for the first time, a frequency-domain Bell-state analyzer.

Each of these demonstrations represents a primitive but essential function in frequency domain QIP, with the potential of scaling up such fundamental systems into larger processors thanks to ongoing efforts in integrated photonics design. Such large-scale integrated processors would then be well positioned for the application such as interconnecting matter qubits with mismatched frequencies and various quantum communication protocols based on frequency-bin encoding.


National Science Foundation (NSF) ECCS-1407620

National Science Foundation (NSF) ECCS-1839191

National Science Foundation (NSF) ECCS-2034019

National Science Foundation (NSF) DMR-1747426

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


Degree Type

  • Doctor of Philosophy


  • Electrical and Computer Engineering

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Andrew M. Weiner

Additional Committee Member 2

Joseph M. Lukens

Additional Committee Member 3

Mahdi Hosseini

Additional Committee Member 4

Tongcang Li