arXiv subjects

Giacomo Corrielli

Publications and source records attributed to Giacomo Corrielli.

49 records · Page 3Linked to original sources

arXiv2019

Quantum Storage of Frequency-Multiplexed Heralded Single Photons

We report on the quantum storage of a heralded frequency-multiplexed single photon in an integrated laser-written rare-earth doped waveguide. The single photon contains 15 discrete frequency modes separated by 261 MHz and spaning across 4 GHz. It is obtained from a non-degenerate photon pair created via cavity-enhanced spontaneous down conversion, where the heralding photon is at telecom wavelength and the heralded photon is at 606 nm. The frequency-multimode photon is stored in a praseodymium-doped waveguide using the atomic frequency comb (AFC) scheme, by creating multiple combs within the inhomogeneous broadening of the crystal. Thanks to the intrinsic temporal multimodality of the AFC scheme, each spectral bin includes 9 temporal modes, such that the total number of stored modes is about 130. We demonstrate that the storage preserves the non-classical properties of the single photon, and its normalized frequency spectrum.

quant-ph↗

arXiv2018

A six-apertures discrete beam combiners for J-band interferometry

The astronomical J-band (1.25 micrometres) is a relatively untapped wave-band in long-baseline infrared interferometry. It allows access to the photosphere in giant and super-giant stars relatively free from opacities of molecular bands. The J-band can potentially be used for imaging spots in the 1350 nm ionised iron line on slowly rotating magnetically-active stars through spectro-interferometry. In addition, the access to the 1080 nanometres He I line may probe outflows and funnel-flows in T-Tauri stars and allow the study of the star-disk interaction. We present the progress in the development of a six-inputs, J-band interferometric beam combiner based on the discrete beam combiner (DBC) concept. DBCs are periodic arrays of evanescent coupled waveguides which can be used to retrieve simultaneously the complex visibility of every baseline from a multi-aperture interferometer. Existing, planned or future interferometric facilities combine or will combine six or more telescopes at the time, thus increasing the snapshot uv coverage from the interferometric measurements. A better uv coverage will consequently enhance the accuracy of the image reconstruction. The component we are currently developing is manufactured in borosilicate glass using the technique of multi-pass ultrafast laser inscription (ULI), using a mode-locked Yb:KYW laser at the wavelength of 1030 nm, pulse duration of 300 fs and repetition rate of 1 MHz. After annealing, the written components showed a propagation loss less than 0.3 dB/cm and a negligible birefringence at a wavelength of 1310 nm, which makes the components suitable for un-polarized light operation. A single mode fiber-to-component insertion loss of 0.9 dB was measured. Work is currently in progress to characterize the components in spectro-interferometric mode with white light covering the J-band spectrum.

astro-ph.IM↗

arXiv2018

Symmetric polarization insensitive directional couplers fabricated by femtosecond laser waveguide writing

We study analytically the polarization behaviour of directional couplers composed of birefringent waveguides, showing that they can induce polarization transformations that depend on the specific input-output path considered. On the basis of this study, we propose and demonstrate experimentally, by femtosecond laser writing, directional couplers that are free from this problem and also yield a polarization independent power-splitting ratio. More in detail, we devise two different approaches to realize such devices: the first one is based on local birefringence engineering, while the second one exploits ultra-low birefringence waveguides obtained by thermal annealing.

physics.optics↗

arXiv2017

Integrated sources of entangled photons at telecom wavelength in femtosecond-laser-written circuits

Photon entanglement is an important state of light that is at the basis of many protocols in photonic quantum technologies, from quantum computing, to simulation and sensing. The capability to generate entangled photons in integrated waveguide sources is particularly advantageous due to the enhanced stability and more efficient light-crystal interaction. Here we realize an integrated optical source of entangled degenerate photons at telecom wavelength, based on the hybrid interfacing of photonic circuits in different materials, all inscribed by femtosecond laser pulses. We show that our source, based on spontaneous parametric down-conversion, gives access to different classes of output states, allowing to switch from path-entangled to polarization-entangled states with net visibilities above 0.92 for all selected combinations of integrated devices.

quant-ph↗

arXiv2017

Geometrically-controlled polarisation processing in an integrated photonic platform

The polarisation of light is a powerful and widely used degree of freedom to encode information, both in classical and quantum applications. In particular, quantum information technologies based on photons are being revolutionised by the use of integrated photonic circuits. It is therefore very important to be able to manipulate the polarisation of photons in such circuits. We experimentally demonstrate the fabrication by femtosecond laser micromachining of components such as polarisation insensitive or polarising directional couplers, operating at 1550 nm wavelength, where the two opposite behaviours are achieved just by controlling the geometric layout of the photonic circuits, being the waveguides fabricated with the same irradiation recipe. We expect to employ this approach in complex integrated photonic devices, capable of a full control of the photons polarisation for quantum cryptography, quantum computation and quantum teleportation experiments.

physics.optics↗

arXiv2016

Experimental nonlocality-based network diagnostics of mutipartite entangled states

Quantum networks of growing complexity play a key role as resources for quantum computation; the ability to identify the quality of their internal correlations will play a crucial role in addressing the buiding stage of such states. We introduce a novel diagnostic scheme for multipartite networks of entangled particles, aimed at assessing the quality of the gates used for the engineering of their state. Using the information gathered from a set of suitably chosen multiparticle Bell tests, we identify conditions bounding the quality of the entangled bonds among the elements of a register. We demonstrate the effectiveness, flexibility, and diagnostic power of the proposed methodology by characterizing a quantum resource engineered combining two-photon hyperentanglement and photonic-chip technology. Our approach is feasible for medium-sized networks due to the intrinsically modular nature of cluster states, and paves the way to section-by-section analysis of large photonics resources.

quant-ph↗

arXiv2016

Observation of Majorization Principle for quantum algorithms via 3-D integrated photonic circuits

The Majorization Principle is a fundamental statement governing the dynamics of information processing in optimal and efficient quantum algorithms. While quantum computation can be modeled to be reversible, due to the unitary evolution undergone by the system, these quantum algorithms are conjectured to obey a quantum arrow of time dictated by the Majorization Principle: the probability distribution associated to the outcomes gets ordered step-by-step until achieving the result of the computation. Here we report on the experimental observation of the effects of the Majorization Principle for two quantum algorithms, namely the quantum fast Fourier transform and a recently introduced validation protocol for the certification of genuine many-boson interference. The demonstration has been performed by employing integrated 3-D photonic circuits fabricated via femtosecond laser writing technique, which allows to monitor unambiguously the effects of majorization along the execution of the algorithms. The measured observables provide a strong indication that the Majorization Principle holds true for this wide class of quantum algorithms, thus paving the way for a general tool to design new optimal algorithms with a quantum speedup.

quant-ph↗

arXiv2016

An Integrated Optical Memory based on Laser Written Waveguides

We report on the first realization of an integrated optical memory for light based on a laser written waveguide in a doped crystal. Using femto-second laser micromachining, we fabricate waveguides in Pr$^{3+}$:Y$_2$SiO$_5$ crystal. We demonstrate that the waveguide inscription does not affect the coherence properties of the material and that the light confinement in the waveguide increases the interaction with the active ions by a factor 6. We also demonstrate that, analogously to the bulk crystals, we can operate the optical pumping protocols necessary to prepare the population in atomic frequency combs, that we use to demonstrate light storage in excited and spin states of the Praseodymium ions. Our results represent the first realization of laser written waveguides in a Pr$^{3+}$:Y$_2$SiO$_5$ crystal and the first implementation of an integrated on-demand spin wave optical memory. They open new perspectives for integrated quantum memories.

quant-ph↗

arXiv2016

Experimental Perfect Quantum State Transfer

The transfer of data is a fundamental task in information systems. Microprocessors contain dedicated data buses that transmit bits across different locations and implement sophisticated routing protocols. Transferring quantum information with high fidelity is a challenging task, due to the intrinsic fragility of quantum states. We report on the implementation of the perfect state transfer protocol applied to a photonic qubit entangled with another qubit at a different location. On a single device we perform three routing procedures on entangled states with an average fidelity of 97.1%. Our protocol extends the regular perfect state transfer by maintaining quantum information encoded in the polarisation state of the photonic qubit. Our results demonstrate the key principle of perfect state transfer, opening a route toward data transfer for quantum computing systems.

quant-ph↗

arXiv2016

Path-polarization hyperentangled and cluster states of photons on a chip

Encoding many qubits in different degrees of freedom (DOFs) of single photons is one of the routes towards enlarging the Hilbert space spanned by a photonic quantum state. Hyperentangled photon states (i.e. states showing entanglement in multiple DOFs) have demonstrated significant implications for both fundamental physics tests and quantum communication and computation. Increasing the number of qubits of photonic experiments requires miniaturization and integration of the basic elements and functions to guarantee the set-up stability. This motivates the development of technologies allowing the precise control of different photonic DOFs on a chip. We demonstrate the contextual use of path and polarization qubits propagating within an integrated quantum circuit. We tested the properties of four-qubit linear cluster states built on both DOFs. Our results pave the way towards the full integration on a chip of hybrid multiqubit multiphoton states.

quant-ph↗

arXiv2013

Quantum frequency conversion of quantum memory compatible photons to telecommunication wavelengths

We report an experiment demonstrating quantum frequency conversion of weak light pulses compatible with atomic quantum memories to telecommunication wavelengths. We use a PPLN nonlinear waveguide to convert weak coherent states at the single photon level with a duration of 30ns from a wavelength of 780nm to 1552nm. We measure a maximal waveguide internal (external) conversion efficiency eta_int = 0.41 (eta_ext = 0.25), and we show that the signal to noise ratio (SNR) is good enough to reduce the input photon number below 1. In addition, we show that the noise generated by the pump beam in the crystal is proportional to the spectral bandwidth of the device, suggesting that narrower filtering could significantly increase the SNR. Finally, we demonstrate that the quantum frequency converter can operate in the quantum regime by converting a time-bin qubit and measuring the qubit fidelity after conversion.

quant-ph↗

arXiv2013

Integrated optical waveplates for arbitrary operations on polarization-encoded single-qubits

Integrated photonic technologies applied to quantum optics have recently enabled a wealth of breakthrough experiments in several quantum information areas. Path encoding was initially used to demonstrate operations on single or multiple qubits. However, a polarization encoding approach is often simpler and more effective. Two-qubits integrated logic gates as well as complex interferometric structures have been successfully demonstrated exploiting polarization encoding in femtosecond-laser-written photonic circuits. Still, integrated devices performing single-qubit rotations are missing. Here we demonstrate waveguide-based waveplates, fabricated by femtosecond laser pulses, capable to effectively produce arbitrary single-qubit operations in the polarization encoding. By exploiting these novel components we fabricate and test a compact device for the quantum state tomography of two polarization-entangled photons. The integrated optical waveplates complete the toolbox required for a full manipulation of polarization-encoded qubits on-chip, disclosing new scenarios for integrated quantum computation, sensing and simulation, and possibly finding application also in standard photonic devices.

quant-ph↗

arXiv2013

Fractional Bloch oscillations in photonic lattices

Bloch oscillations, the oscillatory motion of a quantum particle in a periodic potential, are one of the most fascinating effects of coherent quantum transport. Originally studied in the context of electrons in crystals, Bloch oscillations manifest the wave nature of matter and are found in a wide variety of different physical systems. Here we report on the first experimental observation of fractional Bloch oscillations, using a photonic lattice as a model system of a two-particle extended Bose-Hubbard Hamiltonian. In our photonic simulator, the dynamics of two correlated particles hopping on a one-dimensional lattice is mapped into the motion of a single particle in a two-dimensional lattice with engineered defects and mimicked by light transport in a square waveguide lattice with a bent axis.

quant-ph↗