We employ SPDC in an AlGaAs chip to engineer the wavefunction and exchange statistics of photon pairs directly at the generation stage. We simulate fermions, anyons, and we generate hybrid frequency-polarization entangled states for applications in quantum information.
High-dimensional entangled states of light provide novel capabilities for quantum information, from fundamental tests of quantum mechanics to enhanced computation and communication protocols. In this context, the frequency degree of freedom is attracting a growing interest due to its robustness to propagation in optical fibers and its capability to convey large scale of quantum information into a single spatial mode. This provides a strong incentive for the development of efficient and scalable methods for the generation and manipulation of frequency-encoded quantum states. Nonlinear parametric processes are powerful tools to generate such states, but up to now the manipulation of the generated frequency states has been carried out mostly by post-manipulation, which demands complex and bulk-like experimental setups. Direct production of on-demand frequency-states at the generation stage, and preferably using a chip-based source, is crucial in view of practical and scalable applications for quantum information technologies. Here we employ parametric down-conversion in an integrated AlGaAs chip to engineer the wavefunction and exchange statistics of frequency-entangled photon pairs directly at the generation stage, without post-manipulation [1]. Tuning the pump spatial intensity allows to produce frequency-anticorrelated, correlated and separable states, while tuning the spatial phase allows to tailor the symmetry of the spectral wavefunction. As revealed by Hong-Ou-Mandel interferometry, this allows to simulate either bosons, fermions, or anyons, i.e. particles displaying a fractional exchange statistics intermediate between bosons and fermions [2]. Finally, we show that the frequency entanglement can be combined with the polarization entanglement of our source to produce hybrid frequency-polarization entangled states [3], leading to quantum beating in two-photon interference. These results, obtained at room temperature and telecom wavelength, open promising perspectives for implementing quantum simulation tasks with tailored wavefunction and particle statistics in a chip-integrated platform. [1] S. Francesconi et al, Optica 7, 316 (2020). [2] S. Francesconi et al., ACS Photonics 8, 2764 (2021). [3] S. Francesconi et al., in preparation.
High-dimensional entangled states of light provide novel possibilities for quantum information, from fundamental tests of quantum mechanics to enhanced computation and communication protocols. In this context, the frequency degree of freedom combines the assets of robustness to propagation and easy handling with standard telecommunication components. Here, we use an integrated semiconductor chip to engineer the wavefunction and exchange statistics of frequency-entangled photon pairs directly at the generation stage, without post-manipulation. Tailoring the spatial properties of the pump beam allows generating frequency-anticorrelated, correlated and separable states, and to control the symmetry of the spectral wavefunction to induce either bosonic or fermionic behaviors. These results, obtained at room temperature and telecom wavelength, open promising perspectives for the quantum simulation of fermionic problems with photons on an integrated platform, as well as for communication and computation protocols exploiting antisymmetric high-dimensional quantum states.
High-dimensional entangled states of light provide novel possibilities for quantum information, from fundamental tests of quantum mechanics to enhanced computation and communication protocols. In this context, the frequency degree of freedom is particular attractive thanks to its robustness to propagation in optical fibers and its capability to convey large scale of quantum information into a single spatial mode. This provides a strong incentive for the development of efficient and scalable methods for the generation and the manipulation of frequency-encoded quantum states. Nonlinear parametric processes are powerful tools to generate such states, but up to now the manipulation of the generated frequency states has been carried out mostly by post-manipulation, which demands complex and bulk-like experimental setups. Direct production of on-demand frequency-states at the generation stage, and if possible using a chip-based source, is crucial in view of practical and scalable applications for quantum information technologies. Here we use an integrated semiconductor chip to engineer the wavefunction and exchange statistics of frequency-entangled photon pairs directly at the generation stage, without post-manipulation. Tuning the pump spatial intensity allows to produce frequency-anticorrelated, correlated and separable states, while tuning the spatial phase enables to switch between symmetric and antisymmetric spectral wavefunctions, leading respectively to bosonic and fermionic behaviors of the photons. We also demonstrate the generation of non-Gaussian entanglement in the continuous variables formed by the frequency and time degrees of freedom of the photon pairs. These results, obtained at room temperature and telecom wavelength, and with a chip-based source, open promising perspectives for the quantum simulation of fermionic problems with photons on an integrated platform, as well as for communication and computation protocols exploiting antisymmetric high-dimensional quantum states.
Anyons, particles displaying a fractional exchange statistics intermediate between bosons and fermions, play a central role in the fractional quantum Hall effect and various spin lattice models, and have been proposed for topological quantum computing schemes due to their resilience to noise. Here we use parametric down-conversion in an integrated semiconductor chip to generate biphoton states simulating anyonic particle statistics, in a reconfigurable manner. Our scheme exploits the frequency entanglement of the photon pairs, which is directly controlled through the spatial shaping of the pump beam. These results, demonstrated at room temperature and telecom wavelength on a chip-integrated platform, pave the way to the practical implementation of quantum simulation tasks with tailored particle statistics.
Anyons, particles displaying a fractional exchange statistics intermediate between bosons and fermions, play a central role in the fractional quantum Hall effect and various spin–lattice models, and have been proposed for topological quantum computing schemes due to their resilience to noise. Here we use parametric down-conversion in an integrated semiconductor chip to generate biphoton states simulating anyonic particle statistics in a reconfigurable manner. Our scheme exploits the frequency entanglement of the photon pairs, which is directly controlled through the spatial shaping of the pump beam. These results, demonstrated at room temperature and telecom wavelength on a chip-integrated platform, pave the way to the practical implementation of quantum simulation tasks with tailored particle statistics.
Quantum states of photons such as entangled and single photons are indispensable components for applications in optical quantum information processing. Being able to generate and manipulate quantum states of photons on a chip is a crucial step towards realizing real-world quantum information processing systems such as an optical quantum computer. In this thesis, theoretical and experimental research was carried out for on-chip generation of quantum states of photons via the nonlinear process of spontaneous parametric down-conversion (SPDC), including polarization entangled photons, hyperentangled photons and heralded pure single photons. A majority of the study was based on III-V semiconductor AlGaAs, which could lead to monolithic integration of pump lasers and enable electrically pump sources operating at room temperature. The generation of cross-polarized entangled photons via a type-II SPDC in an AlGaAs Bragg reflection waveguide (BRW) was first investigated. The lack of material birefringence enables the direct generation of wavelength-multiplexed polarization entangled photons with a concurrence of at least 0.77 in a bandwidth of 95 nm. Second, a technique using concurrent type-0 and type-I processes on an AlGaAs chip to generate polarization entangled photon was developed. This technique allows the generation of both co-polarized and cross-polarized entangled photons on the same chip without the need of off-chip compensation, interferometer and bandpass filter. Third, a technique of generating hyperentangled photons on an AlGaAs chip was developed by utilizing spatial modes of different guiding mechanisms. High quality entanglement could be achieved with bandpass filtering of a few nanometers without off-chip phase compensation. Four, a generic technique using nonlinear photonic nanowires to engineer two-photon quantum states was proposed. Via dispersion engineering which controls the group velocity of each mode, maximally entangled polarization entangled photons and pure heralded single photons can be generated on-chip. Design examples were applied to III-V semiconductor and ferroelectric materials. Last, a strategy to enhance the bandwidths of wavelength conversion and SPDC spectrum was developed by tapering the waveguides. Combined with further integration of pump lasers, photonic circuits and detectors, the techniques developed in this thesis provides a viable route to achieve fully integrated generation and manipulations of photonic quantum qubits.