Imperial College London

DrSamueleGrandi

Faculty of Natural SciencesDepartment of Physics

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s.grandi

 
 
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613Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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18 results found

Lago-Rivera D, Grandi S, Rakonjac JV, Seri A, de Riedmatten Het al., 2021, Telecom-heralded entanglement between multimode solid-state quantum memories, NATURE, Vol: 594, Pages: 37-+, ISSN: 0028-0836

Journal article

Burdekin P, Grandi S, Newbold R, Hoggarth RA, Major KD, Clark ASet al., 2020, Single-Photon-Level Sub-Doppler Pump-Probe Spectroscopy of Rubidium, PHYSICAL REVIEW APPLIED, Vol: 14, ISSN: 2331-7019

Journal article

Grandi S, Nielsen MP, Cambiasso J, Boissier S, Major K, Reardon C, Krauss TF, Oulton R, Hinds E, Clark Aet al., 2019, Hybrid plasmonic waveguide coupling of photons from a single molecule, APL Photonics, Vol: 4, Pages: 086101-1-086101-6, ISSN: 2378-0967

We demonstrate the emission of photons from a single molecule into a hybrid gap plasmon waveguide (HGPW). Crystals of anthracene, doped with dibenzoterrylene (DBT), are grown on top of the waveguides. We investigate a single DBT molecule coupled to the plasmonic region of one of the guides, and determine its in-plane orientation, excited state lifetime and saturation intensity. The molecule emits light into the guide, which is remotely out-coupled by a grating. The second-order autocorrelation and cross-correlation functions show that the emitter is a single molecule and that the light emerging from the grating comes from that molecule. The couplinge fficiency is found to be βWG = 11.6(1:5)%. This type of structure is promising for building new functionality into quantum-photonic circuits, where localised regions of strong emitter-guide coupling can be interconnected by low-loss dielectric guides.

Journal article

Grandi S, Nielsen MP, Cambiasso J, Boissier S, Major KD, Reardon C, Krauss TF, Oulton RF, Hinds EA, Clark ASet al., 2019, Hybrid plasmonic waveguide coupling of photons from a single molecule

We demonstrate the emission of photons from a single molecule into a hybridgap plasmon waveguide (HGPW). Crystals of anthracene, doped withdibenzoterrylene (DBT), are grown on top of the waveguides. We investigate asingle DBT molecule coupled to the plasmonic region of one of the guides, anddetermine its in-plane orientation, excited state lifetime and saturationintensity. The molecule emits light into the guide, which is remotelyout-coupled by a grating. The second-order auto-correlation andcross-correlation functions show that the emitter is a single molecule and thatthe light emerging from the grating comes from that molecule. The couplingefficiency is found to be $\beta_{WG}=11.6(1.5)\%$. This type of structure ispromising for building new functionality into quantum-photonic circuits, wherelocalised regions of strong emitter-guide coupling can be interconnected bylow-loss dielectric guides.

Working paper

, 2019, Novel method of sub-wavelength thin film growth for single photon emission from dye molecules

Conference paper

Boissier S, Schofield R, Major K, Grandi S, Boissier S, Hinds E, Clark Aet al., 2018, Efficient excitation of dye molecules for single photon generation, Journal of Physics Communications, Vol: 2, ISSN: 2399-6528

A reliable photon source is required for many aspects of quantum technology. Organic molecules are attractive for this application because they can have high quantum yield and can be photostable, even at room temperature. To generate a photon with high probability, a laser must excite the molecule efficiently. We develop a simple model for that efficiency and discuss how to optimise it. We demonstrate the validity of our model through experiments on a single dibenzoterrylene (DBT) molecule in an anthracene crystal. We show that the excitation probability cannot exceed 75% at room temperature, but can increase to over 99% if the sample is cooled to liquid nitrogen temperature. The possibility of high photon generation efficiency with only modest cooling is a significant step towards a reliable photon source that is simple and practical.

Journal article

Grandi S, Zavatta A, Bellini M, Paris MGAet al., 2017, Experimental quantum tomography of a homodyne detector, New Journal of Physics, Vol: 19, ISSN: 1367-2630

We suggest and demonstrate a tomographic method to characterise homodyne detectors at the quantum level. The positive operator measure associated with the detector is expanded in a quadrature basis and probed with a set of coherent states. The coefficients of the expansion are then retrieved using a least squares algorithm. Our model is general enough to describe different implementations of the homodyne setup, and it has proven capable of effectively describing the detector response to different tomographic sets. We validate the reconstructed operator measure on nonclassical states and exploit results to estimate the overall quantum efficiency of the detector.

Journal article

Polisseni C, Major KD, Boissier S, Grandi S, Clark AS, Hinds EAet al., 2016, Coupling dye molecules to a silicon nitride waveguide, Australian Conference on Optical Fibre Technology (ACOFT)

© OSA 2016. A dibenzoterrylene (DBT) molecule can emit single-photons into a waveguide. We have grown and characterised thin, DBT-doped anthracene crystals on photonic structures, including a silicon nitride ridge waveguide from which we detect single-photons.

Conference paper

Polisseni C, Major K, Boissier S, Grandi S, Clark A, Hinds EAet al., 2016, A stable, single-photon emitter in a thin organic crystal for application to quantum-photonic devices, Optics Express, ISSN: 1094-4087

Journal article

major K, lien Y, polisseni C, grandi S, kho K, clark A, hwang J, Hinds EAet al., 2015, Growth of optical-quality anthracene crystals, doped with dibenzoterrylenefor controlled single photon production, Review of Scientific Instruments, Vol: 86, ISSN: 1089-7623

Dibenzoterrylene (DBT) molecules within a crystalline anthracene matrix show promise as quantum emitters for controlled, single photon production. We present the design and construction of a chamber in which we reproducibly grow doped anthracene crystals of optical quality that are several mm across and a few micrometres thick. We demonstrate control of the DBT concentration over the range 6 { 300 parts per trillion and show that these DBT molecules are stable single-photon emitters. We interpret our data with a simple model that provides some information on the vapour pressure of DBT.

Journal article

Costanzo LS, Zavatta A, Grandi S, Bellini M, Jeong H, Kang M, Lee S-W, Ralph TCet al., 2015, Properties of hybrid entanglement between discrete- and continuous-variable states of light, PHYSICA SCRIPTA, Vol: 90, ISSN: 0031-8949

Journal article

Polisseni C, Kho KW, Grandi S, Major K, Lien YH, Hwang J, Clark AS, Hinds EAet al., 2015, Novel method of sub-wavelength thin film growth for single photon emission from dye molecules

Conference paper

Costanzo LS, Zavatta A, Grandi S, Bellini M, Jeong H, Kang M, Lee S-W, Ralph TCet al., 2014, Experimental hybrid entanglement between quantum and classical states of light, INTERNATIONAL JOURNAL OF QUANTUM INFORMATION, Vol: 12, ISSN: 0219-7499

Journal article

Polisseni C, Kho KW, Grandi S, Major K, Lien YH, Hwang J, Clark AS, Hinds EAet al., 2014, Novel method of sub-wavelength thin film growth for single photon emission from dye molecules

Conference paper

Jeong H, Zavatta A, Kang M, Lee S-W, Costanzo LS, Grandi S, Ralph TC, Bellini Met al., 2014, Generation of hybrid entanglement of light, NATURE PHOTONICS, Vol: 8, Pages: 564-569, ISSN: 1749-4885

Journal article

Rahimi-Keshari S, Kiesel T, Vogel W, Grandi S, Zavatta A, Bellini Met al., 2013, Quantum Process Nonclassicality, PHYSICAL REVIEW LETTERS, Vol: 110, ISSN: 0031-9007

Journal article

Rakonjac JV, Lago-Rivera D, Seri A, Mazzera M, Grandi S, Riedmatten HDet al., Entanglement between a telecom photon and an on-demand multimode solid-state quantum memory

Entanglement between photons at telecommunication wavelengths and long-livedquantum memories is one of the fundamental requirements of long-distancequantum communication. Quantum memories featuring on-demand read-out andmultimode operation are additional precious assets that will benefit thecommunication rate. In this work we report the first demonstration ofentanglement between a telecom photon and a collective spin excitation in amultimode solid-state quantum memory. Photon pairs are generated through widelynon-degenerate parametric down-conversion, featuring energy-time entanglementbetween the telecom-wavelength idler and a visible signal photon. The latter isstored in a Pr$^{3+}$:Y$_2$SiO$_5$ crystal as a spin wave using the full AtomicFrequency Comb scheme. We then recall the stored signal photon and analyze theentanglement using the Franson scheme. We measure conditional fidelities of$92(2)\%$ for excited-state storage, enough to violate a CHSH inequality, and$77(2)\%$ for spin-wave storage. Taking advantage of the on-demand read-outfrom the spin state, we extend the entanglement storage in the quantum memoryfor up to 47.7~$\mu$s, which could allow for the distribution of entanglementbetween quantum nodes separated by distances of up to 10 km.

Journal article

Yamada R, Grandi S, Muñoz-Gil G, Barbiero L, Aloy A, Lewenstein Met al., Applications of Quantum Randomness: From Rabi Oscillations to Fourier Axis Controlling the Musical Timbre, International Journal of Music Science, Technology and Art 3 (2), 17-25 (2021)

Randomness has attracted great interest in the field of music composition forquite some time. As early as 1962, Iannis Xenakis started exploring astochastic approach to randomness by using computer-based interlinkingprobability functions to determine compositional structure, pitches and theirdurations. Soon after, composers and music technologists started to explorerandomness with various methods of algorithmic compositions, sometimes with thehelp of artificial intelligence. However, in most cases, the source ofrandomness they used was in fact deterministic in nature. That is to say, therandom numbers that they employed are imperfect in the strict sense (simplyput, perfect random numbers never have repeating patterns). Moreover, themethod in which they produced such randomness was extrinsic to the method inwhich randomness was applied. In this project, we attempt to take a furtherstep by directly producing sound events from the genuine quantum truerandomness of quantum physical systems. Through this method, we aim atachieving a new sense of aesthetic effect in music which derives from the truerandomness that prevails in the natural quantum world.

Journal article

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