In this paper polarization and hybrid entangled source of light which were built using a fully on-chip battery-powered source of entangled photons will be discussed. These devices use monolithically integrated Bragg reflection waveguide laser diode (BRL) enabling high fidelity, record flux, compact photon pairs to be generated via a type-II intracavity phase-matching process. Furthermore, our turnkey source of entangled photon pairs operates at room temperature and does not require any external components or compensation. These qualities enable our chip to be optimal for highly scalable sources and remote operation. In addition, this talk will also discuss the first on-chip phase-sensitive amplifier utilizing χ(2) nonlinearity. These devices demonstrated the highest reported gain per unit length (devices with effective length ~ 0.1 mm providing gain exceeding 28 dB). Unique to χ(2) nonlinearity is that it also permits a pump that is spectrally far separated from the interacting signal and idler, allowing the highest reported sensitivity in any phase-sensitive amplifier (amplification capability down to an input of 0.005 photon per pulse). One of the main advantages of phase-sensitive amplifiers is their ability to reach a 0 dB noise figure, which enables many applications in quantum photonics.
In this paper polarization and hybrid entangled source of light which were built using a fully on-chip battery-powered source of entangled photons will be discussed. These devices use monolithically integrated Bragg reflection waveguide laser diode (BRL) enabling high fidelity, record flux, compact photon pairs to be generated via a type-II intracavity phase-matching process. Furthermore, our turnkey source of entangled photon pairs operates at room temperature and does not require any external components or compensation. These qualities enable our chip to be optimal for highly scalable sources and remote operation. In addition, this talk will also discuss the first on-chip phase-sensitive amplifier utilizing χ(2) nonlinearity. These devices demonstrated the highest reported gain per unit length (devices with effective length ~ 0.1 mm providing gain exceeding 28 dB). Unique to χ(2) nonlinearity is that it also permits a pump that is spectrally far separated from the interacting signal and idler, allowing the highest reported sensitivity in any phase-sensitive amplifier (amplification capability down to an input of 0.005 photon per pulse). One of the main advantages of phase-sensitive amplifiers is their ability to reach a 0 dB noise figure, which enables many applications in quantum photonics.
This talk will describe a technology that enables the utilization of second order nonlinearities, Chi(2) in monolithic semiconductors to be used as an optimal tool box for quantum optics. This approach uses dispersion engineering in Bragg reflection waveguides to harness parametric processes to produce non classical sources through down conversion [1-4]. These can also be realized in conjunction with concomitant dispersion and birefringence engineering in active devices such as semiconductor diode lasers [5-9]. On the classical front, the technology enables novel coherent light sources using frequency conversion in a self pumped chip-form factor. Novel sources for non-classical states of photons in this monolithic platform will be reviewed. These chip-based sources can afford the integration of other devices such as laser pump sources, power and polarization splitters, gates, cavities and much more. This platform essentially offers the capability of transferring current quantum optical setups from the optical table in a lab into a practical realm and even the market place. Also in this talk, some of the application that utilize the aforementioned sources will be discussed, including monolithic photonics architectures that enable deterministic splitting of entangled states of light will be discussed. In addition, sources for target detection and sensing protocols such as quantum illumination in integrated architectures will be also presented. The attributes of this platform offer unique opportunities in metrology applications where size, power, form-factor and space qualification are important factors.
We demonstrate the first all-on-chip source of entangled photons in polarization or time-energy. Our source is a monolithic Bragg reflection laser diode with intracavity phase matching, enabling a type-II spontaneous parametric down-conversion process. This plug-and-play, electrically injected chip source operates at room temperature and does not require active stabilization. The entangled biphoton state emitted from the chip is in the telecom band, with a bandwidth of 5.56 THz, achieving a pair rate of 5.6 × 105pairs/s. Additionally, a visibility of 76.2% and 58% was obtained for the polarization and time-energy entanglements, respectively. Hence, our source opens the possibility for massively parallel systems from a compact and low-power chip.
Integrated quantum photonics can realize and process optical entangled quantum states in highly compact, robust, and scalable chips thereby enabling chip scale implementations of long-distance quantum-secured communication, quantum-accelerated information processing, and non-classical metrology [1]. Notably, all previous on-chip entangled quantum photonic sources have relied on an external laser to excite nonlinear parametric processes, thereby making these systems overall non-reproducible, bulky, impractical, and thus unsuitable for out-of-lab use as well as production at large scale [2]. To date, the major challenge inhibiting a fully on-chip quantum light system is to integrate a stable, tunable laser together with a high rejection filter that eliminates laser sideband noise [3], [4] and a nonlinear parametric source of entangled photons. Fig. 1 A) laser-integrated photonic quantum light source of frequency-bin entangled photon states: an electrically pumped inp gain-section, i.e. A reflective semiconductor optical amplifier (rsoa) providing optical gain, is coupled to a si3n4 chip containing a three microring resonator (r1, r2, and r3) vernier filter and a mach-zehnder interferometer (mzi) with a sagnac loop mirror. B) measurements utilizing single photon detectors allowed to determine an smsr≈ 112 db, and an ase suppression of> 56 db. C) car for respective frequency pairs for an excitation power of 3.9 mw. D) density matrices of two-dimensional (qubit) and three-dimensional (qutrit) frequency-bin entangled states reconstructed via quantum state tomography (qst).
Abstract Integrated photonics has recently become a leading platform for the realization and processing of optical entangled quantum states in compact, robust, and scalable chip formats with applications in long-distance quantum-secured communication, quantum-accelerated information processing, and non-classical metrology. However, the quantum light sources developed so far have relied on external bulky excitation lasers making them impractical, not reproducible prototype devices, hindering scalability and the transfer out of the lab into real-world applications. Here we demonstrate a fully integrated quantum light source, which overcomes these challenges through the combined integration of a laser cavity, a highly efficient tunable noise suppression filter (> 55 dB) exploiting the Vernier effect, and a nonlinear microring for entangled photon pair generation through spontaneous four-wave mixing. The hybrid quantum source employs an electrically-pumped InP gain section and a Si₃N₄ low-loss microring filter system and demonstrates high-performance parameters, i.e., a pair emission over four resonant modes in the telecom band (bandwidth ∼ 1 THz), and a remarkable pair detection rate of ∼ 620 Hz at a high coincidence-to-accidental ratio of ∼80. The source directly creates high-dimensional frequency-bin entangled quantum states (qubits/qudits), verified by quantum interference measurements with visibilities up to 96% (violating Bell-inequality) and by density matrix reconstruction through state tomography showing fidelities of up to 99%. Our approach, leveraging a hybrid photonic platform, enables commercial-viable, low-cost, compact, light-weight, and field-deployable entangled quantum sources, quintessential for practical, out-of-lab applications, e.g., in quantum processors and quantum satellite communications systems.
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.
Large-scale integrated sources of quantum light are enabling ingredients for the future of photonic quantum technologies. For such platforms, sources based on electrical injection are of value for their turnkey operation, as they do not rely on bulky off-chip sources to achieve quantum nonlinear conversion. This work presents the first demonstration of a source of entangled photons fully contained in a single waveguide. Our source is based on a single battery-powered Bragg reflection waveguide diode laser producing two indistinguishable sources of ultra-broadband polarization-entangled photons. The output state of our device has a Bell-state fidelity of 86.3% without accidental subtraction, a high entangled pair generation rate of 1.16 × 106 (pairs)/(s ⋅ mW ⋅ facet), and an ultra-broadband entangled photon pair bandwidth >5.22 THz. Our approach yields scalable, compact, low-power, and stable sources of polarization-entangled photons, needed for real-world applications of quantum communications and network systems.