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Research Studies on Photons and Biphotons

Stephen E. Harris

Published Oct 1, 2013• 0 citations
OpenAlex

Abstract

Abstract : The central theme of the work on this contract has been: development of techniques and ideas for the control of the waveforms of single photons and the extension of the concepts of nonlinear optics into the x-ray portion of the electromagnetic spectrum. Advances in the first portion of this work include: the first demonstration of use of spread spectrum technology at the single photon level, and in particular the demonstration that it is possible to hide a single photon in an environment of a much higher density of photons with the same spectral power density, and the first demonstration of the technique of chirp and compress, again at the level of a single photon. Key contributions and advances in the hard x-ray portion of this work include: The invention of a new technique for the generation of polarization entangled x-ray biphotons (theoretical), and the demonstration of parametric down conversion in the Langevin regime. Recently, a paper describing the first demonstration of second harmonic generation at x-ray wavelengths has been submitted.

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Quantum Enhanced X-ray Detection

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We present the first experimental demonstration of quantum enhanced detection at x-ray wavelengths.We show that x-ray pairs that are generated by spontaneous down-conversion can be used for the generation of heralded x-ray photons and directly measure the sub-Poissonian statistics of the single photons by using photon number resolving detectors.We utilize the properties of the strong time-energy correlations of the down-converted photons to demonstrate the ability to improve the visibility and the signal-to-noise ratio of an image with a small number of photons in an environment with a noise level that is higher than the signal by many orders of magnitude.A long-term goal of this work is to demonstrate x-ray photon entanglement.However, given the technical challenges, which are much greater than in the visible regime, we take a first step in demonstrating nonclassical (sub-Poisson) photon correlations.In our work, we demonstrate a new protocol for the measurement of quantum effects with x rays using advantages such as background-free measurements that the x-ray regime offers for experiments aiming at testing fundamental concepts in quantum optics.

arXiv:1907.04045•Physical Review X•Aug 23, 2019•34 citations

Toward Single-Cycle Biphotons

Stephen E. Harris, Steven Sensarn

The paper describes a technique for the spontaneous generation of chirped biphotons and for the compression of these photons to transform limited biphotons. At maximum bandwidth the biphoton is a single-cycle in length and has the waveform of a classical single-cycle pulse. Without compression, chirped biphotons still exhibit a Hong- Ou-Mandel dip with a width approximately equal to the inverse spectral width of the biphoton.

The Rochester Conferences on Coherence and Quantum Optics and the Quantum Information and Measurement meeting•Jan 1, 2007•3 citations

Efficient Entangled Biphoton Production and Manipulation for Quantum Applications

Hannah E. Guilbert

The creation and manipulation of biphotons is important for many applications in quantum optics and quantum information. Topics that benefit from efficient biphoton sources range from the most fundamental quantum science experiments to the highly applied fields of quantum communication and quantum computation. Biphoton sources have long been hailed as one of the leading methods for creating entangled photon pairs for tests of Bell's inequality, creating heralded photon pairs that are used in on-demand single-photon sources and heralded measurement techniques, and for quantum communication protocols to name a few. Specifically for quantum communication, biphoton sources are commonly used for cutting edge quantum key distribution (QKD) protocols. In the first part of the thesis, I focus on realizing an efficient biphoton source that produces high yield photon pairs. More specifically, I develop an optimized biphoton source using the nonlinear optical process of spontaneous parametric down-conversion in a second-order nonlinear crystal. I develop a formalism for predicting the two important metrics of a biphoton source: the heralding efficiency and joint count rate. I show how, from a large parameter space, one can tailor the phase matching of the nonlinear interaction to create a high quality biphoton source that produces both high heralding efficiency and high joint count rate. I achieve heralding efficiencies of 86$\\pm$5$\\%$ and joint count rates of 2.58$\\pm$0.6 kHz per mW pump power. I show that using a collinear nondegenerate geometry allows for heralding efficiencies of up to 99.7$\\%$ assuming no loss in the system. I verify the theoretical model with experimental results and find good agreement. In the second part of the thesis I turn to manipulating the single photons born from the biphoton source for applications in creating single-photon spectrometers and time-frequency QKD systems. The security of QKD is only guaranteed if the two parties have access to a set of states called mutually unbiased states. I create a set of these states in time and their conjugate states in the frequency basis and show that I can manipulate single photon correlations in time and frequency so that an eavesdropper can be detected if she localizes a photon to a 1 ns time interval. Additionally, in these experiments, I stretch a single photon wavepacket of 5-ps-width to a wavepacket of 8.3-ns-width and subsequently recompress it to at least the resolution of the detectors ($\\sim$ 300 ps). This demonstrates a stretch factor of >1600 for a single-photon pulse using a group velocity dispersive material. To my knowledge, this is the largest reported stretch factor for a single-photon wavepacket produced by a biphoton source. The ability to stretch and recompress a single photon by this amount has applications in creating high-resolution, high-efficiency, single-photon spectrometers as well as advancing time-frequency QKD systems and other temporal pulse shaping applications.

•Jan 1, 2015•0 citations

Chirp and Compress: Toward Single-Cycle Biphotons

Stephen E. Harris

The Letter describes a technique for the spontaneous generation of chirped time-energy entangled photons. Transmitting either photon through an appropriate dispersive medium results in a temporally compressed, transform limited biphoton. At maximum bandwidth, the biphoton is a single cycle in length, with a waveform that has the same characteristic shape as a classical single-cycle pulse.

Physical Review Letters•Feb 5, 2007•162 citations

Generation and Manipulation of Nonclassical Photon Sources in Nonlinear Processes

Zhi‐Yuan Zhou, Bao‐Sen Shi

Nonclassical photon sources are key components in quantum information science and technology. Here, the basic principles and progresses for single photon generation and their further manipulation based on second- or third-order nonlinear processes in various degrees of freedom are briefly reviewed and discussed. Based on spontaneous parametric down-conversion and spontaneous four-wave mixing, various nonlinear materials such as quasi-phase-matching crystals, dispersion-shifted fibers, and silicon-on-insulator waveguides are used for single photon generation. The kinds of entanglement generated include polarization, time-energy, time-bin, and orbital angular momentum. The key ingredient for photon pair generation in nonlinear processes is described and discussed. Besides, we also introduce quantum frequency conversion for converting a single photon from one wavelength to another wavelength, while keeping its quantum properties unchanged. Finally, we give a comprehensive conclusion and discussion about future perspectives for single photon generation and manipulation in nonlinear processes. This chapter will provide an overview about the status, current challenge, and future perspectives about single photon generation and processing in nonlinear processes.

IntechOpen eBooks•Dec 2, 2019•0 citations

Nonlinear optics at the single-photon level

Amir Feizpour

In this thesis I report the first experimental observation of an interaction between a postselected single photon and an electromagnetic field containing a few thousand photons.This is the first observation of the nonlinear interactions due to a single freely propagatingphoton. To achieve this pioneering result, we have theoretically and experimentally studied nonlinear optics at the few-photon level. To the best of our knowledge, the pulse energy levels used for our experiments are the lowest energies used for cross-phase modulation in free space.Photon-photon interaction is vanishingly weak; the strength of this interaction can be enhanced in the presence of a material medium as mediator. In our experiment, we use an atomic coherence effect, namely Electromagnetically-induced Transparency (EIT), to produce a `giant' nonlinear interaction between two optical fields. We have observed a nonlinear phase shift of 18 ± 4 µrad per freely propagating single photon. This is done by sending very weak coherent state pulses into the medium and subsequently detecting single photons, inferring the existence of a photon in the interaction region.The optical setup, electronics and software that have been developed during the completion of this thesis provide the basis for several exciting future light-matter interaction experiments. We have produced phase-stable laser beams to create EIT in our cold Rubidium sample prepared in a Magneto-optical Trap (MOT). The laser system and the improved MOT setup have been built to be stable so that we can do very long data acquisition runs. We also have develop ed to ols and software with high precision and stability such that we can measure phase shifts down to micro-radian level.

•Mar 1, 2015•1 citation
Abstract : The central theme of the work on this contract has been: development of techniques and ideas for the control of the waveforms of single photons and the extension of the concepts of nonlinear optics into the x-ray portion of the electromagnetic spectrum. Advances in the first portion of this work include: the first demonstration of use of spread spectrum technology at the single photon level, and in particular the demonstration that it is possible to hide a single photon in an environment of a much higher density of photons with the same spectral power density, and the first demonstration of the technique of chirp and compress, again at the level of a single photon. Key contributions and advances in the hard x-ray portion of this work include: The invention of a new technique for the generation of polarization entangled x-ray biphotons (theoretical), and the demonstration of parametric down conversion in the Langevin regime. Recently, a paper describing the first demonstration of second harmonic generation at x-ray wavelengths has been submitted.
We present the first experimental demonstration of quantum enhanced detection at x-ray wavelengths.We show that x-ray pairs that are generated by spontaneous down-conversion can be used for the generation of heralded x-ray photons and directly measure the sub-Poissonian statistics of the single photons by using photon number resolving detectors.We utilize the properties of the strong time-energy correlations of the down-converted photons to demonstrate the ability to improve the visibility and the signal-to-noise ratio of an image with a small number of photons in an environment with a noise level that is higher than the signal by many orders of magnitude.A long-term goal of this work is to demonstrate x-ray photon entanglement.However, given the technical challenges, which are much greater than in the visible regime, we take a first step in demonstrating nonclassical (sub-Poisson) photon correlations.In our work, we demonstrate a new protocol for the measurement of quantum effects with x rays using advantages such as background-free measurements that the x-ray regime offers for experiments aiming at testing fundamental concepts in quantum optics.
The creation and manipulation of biphotons is important for many applications in quantum optics and quantum information. Topics that benefit from efficient biphoton sources range from the most fundamental quantum science experiments to the highly applied fields of quantum communication and quantum computation. Biphoton sources have long been hailed as one of the leading methods for creating entangled photon pairs for tests of Bell's inequality, creating heralded photon pairs that are used in on-demand single-photon sources and heralded measurement techniques, and for quantum communication protocols to name a few. Specifically for quantum communication, biphoton sources are commonly used for cutting edge quantum key distribution (QKD) protocols. In the first part of the thesis, I focus on realizing an efficient biphoton source that produces high yield photon pairs. More specifically, I develop an optimized biphoton source using the nonlinear optical process of spontaneous parametric down-conversion in a second-order nonlinear crystal. I develop a formalism for predicting the two important metrics of a biphoton source: the heralding efficiency and joint count rate. I show how, from a large parameter space, one can tailor the phase matching of the nonlinear interaction to create a high quality biphoton source that produces both high heralding efficiency and high joint count rate. I achieve heralding efficiencies of 86$\\pm555\\%$ and joint count rates of 2.58$\\pm0.6kHzpermWpumppower.Ishowthatusingacollinearnondegenerategeometryallowsforheraldingefficienciesofupto99.70.6 kHz per mW pump power. I show that using a collinear nondegenerate geometry allows for heralding efficiencies of up to 99.70.6kHzpermWpumppower.Ishowthatusingacollinearnondegenerategeometryallowsforheraldingefficienciesofupto99.7\\%$ assuming no loss in the system. I verify the theoretical model with experimental results and find good agreement. In the second part of the thesis I turn to manipulating the single photons born from the biphoton source for applications in creating single-photon spectrometers and time-frequency QKD systems. The security of QKD is only guaranteed if the two parties have access to a set of states called mutually unbiased states. I create a set of these states in time and their conjugate states in the frequency basis and show that I can manipulate single photon correlations in time and frequency so that an eavesdropper can be detected if she localizes a photon to a 1 ns time interval. Additionally, in these experiments, I stretch a single photon wavepacket of 5-ps-width to a wavepacket of 8.3-ns-width and subsequently recompress it to at least the resolution of the detectors (sim\\simsim 300 ps). This demonstrates a stretch factor of >1600 for a single-photon pulse using a group velocity dispersive material. To my knowledge, this is the largest reported stretch factor for a single-photon wavepacket produced by a biphoton source. The ability to stretch and recompress a single photon by this amount has applications in creating high-resolution, high-efficiency, single-photon spectrometers as well as advancing time-frequency QKD systems and other temporal pulse shaping applications.
Nonclassical photon sources are key components in quantum information science and technology. Here, the basic principles and progresses for single photon generation and their further manipulation based on second- or third-order nonlinear processes in various degrees of freedom are briefly reviewed and discussed. Based on spontaneous parametric down-conversion and spontaneous four-wave mixing, various nonlinear materials such as quasi-phase-matching crystals, dispersion-shifted fibers, and silicon-on-insulator waveguides are used for single photon generation. The kinds of entanglement generated include polarization, time-energy, time-bin, and orbital angular momentum. The key ingredient for photon pair generation in nonlinear processes is described and discussed. Besides, we also introduce quantum frequency conversion for converting a single photon from one wavelength to another wavelength, while keeping its quantum properties unchanged. Finally, we give a comprehensive conclusion and discussion about future perspectives for single photon generation and manipulation in nonlinear processes. This chapter will provide an overview about the status, current challenge, and future perspectives about single photon generation and processing in nonlinear processes.
In this thesis I report the first experimental observation of an interaction between a postselected single photon and an electromagnetic field containing a few thousand photons.This is the first observation of the nonlinear interactions due to a single freely propagatingphoton. To achieve this pioneering result, we have theoretically and experimentally studied nonlinear optics at the few-photon level. To the best of our knowledge, the pulse energy levels used for our experiments are the lowest energies used for cross-phase modulation in free space.Photon-photon interaction is vanishingly weak; the strength of this interaction can be enhanced in the presence of a material medium as mediator. In our experiment, we use an atomic coherence effect, namely Electromagnetically-induced Transparency (EIT), to produce a `giant' nonlinear interaction between two optical fields. We have observed a nonlinear phase shift of 18 ± 4 µrad per freely propagating single photon. This is done by sending very weak coherent state pulses into the medium and subsequently detecting single photons, inferring the existence of a photon in the interaction region.The optical setup, electronics and software that have been developed during the completion of this thesis provide the basis for several exciting future light-matter interaction experiments. We have produced phase-stable laser beams to create EIT in our cold Rubidium sample prepared in a Magneto-optical Trap (MOT). The laser system and the improved MOT setup have been built to be stable so that we can do very long data acquisition runs. We also have develop ed to ols and software with high precision and stability such that we can measure phase shifts down to micro-radian level.