Tailoring nonlinear processes for quantum optics with pulsed temporal-mode encodings

Ansari, Vahid; Donohue, John M.; Brecht, Benjamin; Silberhorn, Christine

doi:10.1364/optica.5.000534

Cited by 140 publications

(115 citation statements)

References 174 publications

(238 reference statements)

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“…Conveniently, this decomposition also provides the spectral modal structure of the PDC biphoton state. TFMs can therefore be engineered by shaping the JSA, either by modifying the pump-pulse amplitude function [10] or, as we demonstrate here, by shaping the PMF via nonlinearity engineering. Domain-engineered crystals have been employed successfully for the generation of spectrally-pure heralded photons [18,19], where undesired frequency correlations are eliminated by tailoring a Gaussian nonlinearity profile.…”

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confidence: 94%

“…We experimentally validate this technique by benchmarking a maximally antisymmetric state at telecom wavelength † These two authors contributed equally.with near unity fidelity, and implement a four-photon entanglement swapping scheme. Our work complements the pulse-gate toolbox [5,10] for TFM quantum information processing, and establishes a standard for the generation of TFM quantum states of light while paving the way for more complex frequency encoding.In a PDC process, a pump photon probabilistically downconverts into two photons under momentum and energy conservation. The second-order nonlinearity of a crystal mediates the process through the phase-matching function (PMF) which, together with the pump spectral profile, dictates the spectral properties of the output biphoton state in the form of its joint spectral amplitude (JSA).…”

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confidence: 95%

“…We employ this technique in a four-photon entanglement swapping scheme as a primitive for TFM-encoded quantum protocols.Generating entanglement in intrinsically highdimensional degrees of freedom of light, such as transverse and longitudinal spatial modes [1,2], or time and frequency, constitutes a powerful resource for photonic quantum technologies-photons that carry more information enable more efficient protocols [3,4]. Time-frequency encoding is intrinsically suitable for waveguide integration and fibre transmission [5,6], making it a promising choice for practical, high-dimensional quantum applications.Quantum information can be encoded either in discrete temporal or spectral modes (namely time-and frequency-bin encoding [6-9]) or in the spectral envelope of the singlephoton wavepackets-time-frequency mode (TFM) encoding [5,10]. TFM-encoded states arise naturally in parametric downconversion (PDC) sources, as TFMs are eigenstates of the PDC process and they span an infinite-dimensional Hilbert space.…”

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confidence: 99%

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Direct Generation of Tailored Pulse-Mode Entanglement

et al. 2020

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Photonic quantum technology increasingly uses frequency encoding to enable higher quantum information density and noise resilience. Pulsed time-frequency modes (TFM) represent a unique class of spectrally encoded quantum states of light that enable a complete framework for quantum information processing. Here, we demonstrate a technique for direct generation of entangled TFMencoded states in single-pass, tailored downconversion processes. We achieve unprecedented quality in state generation-high rates, heralding efficiency and state fidelity-as characterised via highly resolved time-of-flight fibre spectroscopy and two-photon interference. We employ this technique in a four-photon entanglement swapping scheme as a primitive for TFM-encoded quantum protocols.Generating entanglement in intrinsically highdimensional degrees of freedom of light, such as transverse and longitudinal spatial modes [1,2], or time and frequency, constitutes a powerful resource for photonic quantum technologies-photons that carry more information enable more efficient protocols [3,4]. Time-frequency encoding is intrinsically suitable for waveguide integration and fibre transmission [5,6], making it a promising choice for practical, high-dimensional quantum applications.Quantum information can be encoded either in discrete temporal or spectral modes (namely time-and frequency-bin encoding [6-9]) or in the spectral envelope of the singlephoton wavepackets-time-frequency mode (TFM) encoding [5,10]. TFM-encoded states arise naturally in parametric downconversion (PDC) sources, as TFMs are eigenstates of the PDC process and they span an infinite-dimensional Hilbert space. Conveniently, TFMs possess highly desirable properties: being centred around a target wavelength makes them compatible with fibre networks, they are robust against noise [11] and chromatic dispersion [12], their pulsed nature enables synchronisation and therefore multi-photon protocols and they offer intrinsically high dimensionality [10]. Manipulation and detection of TFMs is enabled by the quantum-pulse toolbox, where sum-and difference-frequency generation are used for reshaping and projecting the quantum states [5,10]. However, generating entangled TFMs in a controlled way can be very challenging [13][14][15][16][17], limiting their usefulness in realistic scenarios. Here, we overcome this problem exploiting domain-engineered nonlinear crystals [18,19] for generating TFM entanglement from standard ultrafast laser pulses in a single-pass PDC experiment. We experimentally validate this technique by benchmarking a maximally antisymmetric state at telecom wavelength † These two authors contributed equally.with near unity fidelity, and implement a four-photon entanglement swapping scheme. Our work complements the pulse-gate toolbox [5,10] for TFM quantum information processing, and establishes a standard for the generation of TFM quantum states of light while paving the way for more complex frequency encoding.In a PDC process, a pump photon probabilistically downconverts into t...

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confidence: 94%

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confidence: 95%

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confidence: 99%

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Direct Generation of Tailored Pulse-Mode Entanglement

et al. 2020

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“…where n(ω) is the frequency-dependent refractive index that determines the material dispersion, and λ P , λ S , and λ I are the pump, signal, and idler wavelengths [23,26,31]. To quantitatively describe the spectral correlation between the signal and idler, the JSA is decomposed [26,32] to f (ω S , ω I ) = n ξ n β S,n (ω S )β I,n (ω I ). Upon this, the purity is defined as P = n ξ 4 n /( n ξ 2 n ) 2 .…”

Section: Biphoton Jsa and Phase Matchingmentioning

confidence: 99%

Wave-Function Engineering for Spectrally Uncorrelated Biphotons in the Telecommunication Band Based on a Machine-Learning Framework

et al. 2019

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Indistinguishable single photons are key ingredient for a plethora of quantum information processing applications ranging from quantum communications to photonic quantum computing. A mainstream platform to produce indistinguishable single photons over a wide spectral range is based on biphoton generation through spontaneous parametric down-conversion (SPDC) in nonlinear crystals. The purity of the SPDC biphotons, however, is limited by their spectral correlations. Here, we present a design recipe, based on a machine-learning framework, for the engineering of biphoton joint spectrum amplitudes over a wide spectral range. By customizing the poling profile of the KTiOPO4 (KTP) crystal, we show, numerically, that spectral purities of 99.22%, 99.99%, and 99.82% can be achieved, respectively, in the 1310-nm, 1550-nm, and 1600-nm bands after applying a moderate 8-nm filter. The machine-learning framework thus enables the generation of near-indistinguishable single photons over the entire telecommunication band without resorting to KTP crystal's group-velocity-matching wavelength window near 1582 nm.

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“…To study the impact of time-frequency correlations of the state on the four-photon interference, we employ an engineered, programmable PDC source. Our source is an 8 mm long waveguided channel in KTP, engineered to the symmetric group velocity matching condition which allows us to flexibly control the frequency correlation between signal and idler photons by modulating the pump pulses only [33,34]. We pump the source with ultrashort pulses out of an Ti:Sa oscillator, followed by a pulse shaper.…”

Section: A Experimentsmentioning

confidence: 99%

Temporally multimode four-photon Hong-Ou-Mandel interference

et al. 2019

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The two-photon Hong-Ou-Mandel (HOM) interference is a pure quantum effect which indicates the degree of indistinguishability of photons. The four-photon HOM interference exhibits richer dynamics in comparison to the two-photon interference and simultaneously is more sensitive to the input photon states. We demonstrate theoretically and experimentally an explicit dependency of the four-photon interference to the number of temporal modes, created in the process of parametric down-conversion. Moreover, we exploit the splitting ratio of the beam splitter to manipulate the interference between bunching and antibunching. Our results reveal that the temporal mode structure (multimodeness) of the quantum states shapes many-particle interference.

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Tailoring nonlinear processes for quantum optics with pulsed temporal-mode encodings

Cited by 140 publications

References 174 publications

Direct Generation of Tailored Pulse-Mode Entanglement

Direct Generation of Tailored Pulse-Mode Entanglement

Wave-Function Engineering for Spectrally Uncorrelated Biphotons in the Telecommunication Band Based on a Machine-Learning Framework

Temporally multimode four-photon Hong-Ou-Mandel interference

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