Squeezed states are a versatile class of quantum states with applications ranging from quantum computing to high-precision detection. We propose a method for generating tunable squeezed vacuum states of light with multiple modes encoded in frequency bins. Our method uses custom-engineered spontaneous parametric down-conversion pumped by a pulse-shaped pump field. The multimode squeezed states are generated in a single pass and can be tuned in real time by adjusting the properties of the pump field. Exploring new quantum states of light, encoded in new degrees of freedom, can be a fruitful path toward discovering new quantum applications.
2021
Optimised domain-engineered crystals for pure telecom photon sources
Alexander Pickston, Francesco Graffitti, Peter Barrow, and 4 more authors
The ideal photon-pair source for building up multi-qubit states needs to produce indistinguishable photons with high efficiency. Indistinguishability is crucial for minimising errors in two-photon interference, central to building larger states, while high heralding rates will be needed to overcome unfavourable loss scaling. Domain engineering in parametric down-conversion sources negates the need for lossy spectral filtering allowing one to satisfy these conditions inherently within the source design. Here, we present a telecom-wavelength parametric down-conversion photon source that operates on the achievable limit of domain engineering. We generate photons from independent sources which achieve two-photon interference visibilities of up to 98.6 ± 1.1% without narrow-band filtering. As a consequence, we reach net heralding efficiencies of up to 67.5%, which corresponds to collection efficiencies exceeding 90%.
2020
Direct Generation of Tailored Pulse-Mode Entanglement
Francesco Graffitti, Peter Barrow, Alexander Pickston, and 2 more authors
Phys. Rev. Lett., Feb 2020
Multidimensional super- and subradiance in waveguide quantum electrodynamics
Fatih Dinc, Lauren E. Hayward, and Agata M. Brańczyk
Phys. Rev. Res., Oct 2020
Quantum simulation of Unruh-DeWitt detectors with nonlinear optics
Eugene Adjei, Kevin J. Resch, and Agata M. Brańczyk
Phys. Rev. A, Sep 2020
Optimal storage time for N qubits coupled to a one-dimensional waveguide
Tevfik Can Yuce, Fatih Dinc, and Agata M. Brańczyk
Sep 2020
2019
Non-Markovian super-superradiance in a linear chain of up to 100 qubits
Fatih Dinc, and Agata M. Brańczyk
Phys. Rev. Res., Dec 2019
Exact Markovian and non-Markovian time dynamics in waveguide QED: collective interactions, bound states in continuum, superradiance and subradiance
Fatih Dinc, Ercan, and Agata M. Brańczyk
Quantum, Dec 2019
Non-Hermitian engineering for brighter broadband pseudothermal light
Nicolás Quesada, Eugene Adjei, Ramy El-Ganainy, and 1 more author
Phys. Rev. A, Oct 2019
Broadband pseudothermal states with tunable spectral coherence generated via nonlinear optics
Nicolás Quesada, and Agata M. Brańczyk
Phys. Rev. A, Jan 2019
2018
Design considerations for high-purity heralded single-photon sources
Francesco Graffitti, Jérémy Kelly-Massicotte, Alessandro Fedrizzi, and 1 more author
Phys. Rev. A, Nov 2018
Gaussian functions are optimal for waveguided nonlinear-quantum-optical processes
Photonic quantum technology relies on efficient sources of coherent single photons, the ideal carriers of quantum information. Heralded single photons from parametric down-conversion can approximate on-demand single photons to a desired degree, with high spectral purities achieved through group-velocity matching and tailored crystal nonlinearities. Here we propose crystal-nonlinearity-engineering techniques with sub-coherence-length domains. We first introduce a combination of two existing methods: a deterministic approach with coherence-length domains and probabilistic domain-width annealing. We then show how the same deterministic domain-flip approach can be implemented with sub-coherence-length domains. Both of these complementary techniques create highly pure photons, outperforming previous methods, in particular for short nonlinear crystals matched to femtosecond lasers.
Parasitic Photon-Pair Suppression via Photonic Stop-Band Engineering
L. G. Helt, Agata M. Brańczyk, Marco Liscidini, and 1 more author
Phys. Rev. Lett., Feb 2017
Thermal light as a mixture of sets of pulses: the quasi-1D example
The relationship between thermal light and coherent pulses is of fundamental and practical interest. We now know that thermal light cannot be represented as a statistical mixture of single pulses. In this paper, we ask whether or not thermal light can be represented as a statistical mixture of sets of pulses. We consider thermal light in a one-dimensional waveguide, and find a convex decomposition into products of orthonormal coherent states of localized, nonmonochromatic modes.
2016
Shaping the joint spectrum of down-converted photons through optimized custom poling
Annamaria Dosseva, Łukasz Cincio, and Agata M. Brańczyk
Phys. Rev. A, Jan 2016
Thermal States and Wave Packets
Aurélia Chenu, Agata M. Brańczyk, and John E. Sipe
Jan 2016
2015
Thermal Light Cannot Be Represented as a Statistical Mixture of Single Pulses
Aurélia Chenu, Agata M. Brańczyk, Gregory D. Scholes, and 1 more author
Phys. Rev. Lett., May 2015
First-order decomposition of thermal light in terms of a statistical mixture of single pulses
Auré lia Chenu, Agata M. Brańczyk, and J. E. Sipe
Physical Review A, Jun 2015
2014
Crossing disciplines - A view on two-dimensional optical spectroscopy
Agata M. Brańczyk, Daniel B. Turner, and Gregory D. Scholes
Recent interest in the role of quantum mechanics in the primary events of photosynthetic energy transfer has led to a convergence of nonlinear optical spectroscopy, condensed matter and quantum physics on the topic of energy-transfer dynamics in pigment-protein complexes. The convergence of these communities has unveiled a mismatch between the background and terminology of the respective fields. To make connections, a pedagogical guide to understanding the basics of two-dimensional spectra is provided aimed at researchers with a background in quantum mechanics and condensed matter.
Optimization of quantum state tomography in the presence of experimental constraints
Mohammadreza Mohammadi, and Agata M. Brańczyk
Phys. Rev. A, Jan 2014
2013
Self-calibrating tomography for multidimensional systems
Nicolás Quesada, Agata M. Brańczyk, and Daniel F. V. James
Phys. Rev. A, Jun 2013
Fourier-transform quantum state tomography
Mohammadreza Mohammadi, Agata M. Brańczyk, and Daniel F. V. James
Phys. Rev. A, Jan 2013
2012
An excitation-dependent four-level model for quantum entanglement in photosynthetic systems
Chi-Han Chang, Agata M. Branczyk, Gregory D. Scholes, and 1 more author
Jan 2012
2011
Engineered optical nonlinearity for quantum light sources
Agata M. Brańczyk, Alessandro Fedrizzi, Thomas M. Stace, and 2 more authors
Many applications in optical quantum information processing benefit from careful spectral shaping of single-photon wave-packets. In this paper we tailor the joint spectral wave-function of photons created in parametric downconversion by engineering the nonlinearity profile of a poled crystal. We design a crystal with an approximately Gaussian nonlinearity profile and confirm successful wave-packet shaping by two-photon interference experiments. We numerically show how our method can be applied for attaining one of the currently most important goals of single-photon quantum optics, the creation of pure single photons without spectral correlations.
Time Ordering in Spontaneous Parametric Downâconversion
Agata M. Brańczyk, Thomas M. Stace, and T. C. Ralph
AIP Conference Proceedings, Jan 2011
2010
Optimized generation of heralded Fock states using parametric down-conversion
Agata M Brańczyk, T C Ralph, Wolfram Helwig, and 1 more author
The generation of heralded pure Fock states via spontaneous parametric down-conversion (PDC) relies on perfect photon-number correlations in the output modes. Correlations in any other degree of freedom, however, degrade the purity of the heralded state. In this paper, we investigate spectral entanglement between the two output modes of a periodically poled waveguide. With the intent of generating heralded one- and two-photon Fock states, we expand the output state of the PDC to second order in photon number. We explore the effects of spectral filtering and inefficient detection, of the heralding mode, on the count rate, g(2), and purity of the heralded state, as well as the fidelity between the resulting state and an ideal Fock state. We find that filtering can decrease spectral correlations, however, at the expense of the count rate and increased photon-number mixedness in the heralded output state. As a physical example, we model a type II PP-KTP waveguide pumped by lasers at wavelengths of 400ânm, 788ânm and 1.93âÎŒm. The latter two allow the fulfillment of extended phase-matching conditions in an attempt to eliminate spectral correlations in the PDC output state without the use of filtering; however, we find that, even in these cases, some filtering is needed to achieve states of very high purity.
2008
Teleportation using squeezed single photons
Agata M. Brańczyk, and T. C. Ralph
Phys. Rev. A, Nov 2008
2007
Optical tweezers computational toolbox
Timo A Nieminen, Vincent L Y Loke, Alexander B Stilgoe, and 4 more authors
Journal of Optics A: Pure and Applied Optics, Jul 2007
We describe a toolbox, implemented in Matlab, for the computational modelling of optical tweezers. The toolbox is designed for the calculation of optical forces and torques, and can be used for both spherical and nonspherical particles, in both Gaussian and other beams. The toolbox might also be useful for light scattering using either LorenzâMie theory or the T-matrix method.
Quantum control of a single qubit
Agata M. Brańczyk, Paulo E. M. F. ç\fia, Alexei Gilchrist, and 2 more authors
Phys. Rev. A, Jan 2007
2006
Modelling optical micromachines and birefringent particles
Vincent L. Y. Loke, Timo A. Nieminen, Simon J. Parkin, and 3 more authors
In Photonic Devices and Algorithms for Computing VIII, Jan 2006
2003
Photon-added detection
A. M. Brańczyk, Tobias J. Osborne, Alexei Gilchrist, and 1 more author