2,751 research outputs found
Coherent optical ultrasound detection with rare-earth ion dopants
No full textWe describe theoretical and experimental demonstration for optical detection of ultrasound using a spectral hole engraved in cryogenically cooled rare-earth ion-doped solids. Our method utilizes the dispersion effects due to the spectral hole to perform phase-to-amplitude modulation conversion. Like previous approaches using spectral holes, it has the advantage of detection with large étendue. The method also has the benefit that high sensitivity can be obtained with moderate absorption contrast for the spectral holes.</p
Experimental realization of light with time-separated correlations by rephasing amplified spontaneous emission
No full textAmplified spontaneous emission is a common noise source in active optical systems, it is generally seen as being an incoherent process. Here we excite an ensemble of rare earth ion dopants in a solid with a π pulse, resulting in amplified spontaneous emission. The application of a second π pulse leads to a coherent echo of the amplified spontaneous emission that is correlated in both amplitude and phase. For small optical thicknesses, we see evidence that the amplified spontaneous emission and its echo are entangled.</p
Letter from Patrick M. Duignan to Hagan
No full textHolograph letter from Patrick M. Duignan, Summer Hill College Sligo, to Hagan. At the wish of the bishop, enclosing three documents of correspondence between the O'Conor Don, Clonalis, Castlerea, County Roscommon, and Bishop Bernard Coyne, St. Mary's, Sligo: the O'Conor Don recommends his friend Fr. Roche, now of St. John's Church, Brentford, London, for the rectorship at the Irish College. He has good command of Italian (marginal comment 'no Irish!') and is a 'kind zealous and polished priest'. The bishop replies that the present vice-rector �'a distinguished writer and author'- has a prior claim; the O'Conor Don concurs. Duignan offers himself as a potential vice-rector; asking for frank reply. Musing that the bishop's interest in the matter is surprising; he is intolerant of English interference and whole-heartedly supports Hagan
Art, Biography, Sexuality: Patrick Procktor and Keith Vaughan
No full textThis critical review forms a reflection on the research published within the following publications:
Patrick Procktor: Art and Life (Unicorn Press, 2010)
Keith Vaughan: The Mature Oils 1946-1977, (Sansom & Co., 2012)
The research is on two artists, Patrick Procktor (1936-2003), and Keith Vaughan (1912-1977). The monograph on Procktor – previously one of the least documented of the generation of artists who came to prominence in London in the Sixties – positions him in a history of art from which he had been notably absent. The research on Vaughan asserts a new reading of his work, one that is both deeper and more nuanced in its analysis of the ways in which personal experience and sexuality are encoded autobiographically within his work. Crucially, in both artists biography and work are symbiotically linked; the research therefore examines the links between life and art.
Revisionary in intent, the work examines trajectories of experience of gay British (or rather, English) artists in the twentieth century, artists who sought to express themselves and forge careers within the constraints of a heteronormative society, albeit one in which attitudes to sexuality were undergoing change. As gay men, both were constrained by the social mores of their times, and each used painting as a means to affirm personal and sexual identities. A key research interest is in the ways in which sexuality and persona are reflected in critical responses to the artist’s work: in Vaughan, Procktor and other gay male artists of the period. The writing on both Procktor and Vaughan examines the relationship between their personal and professional/artistic lives, framed within a broader socio-political and art historical context. It asserts the place of biography as a means to understand and form new readings of the work. The work adds substantially to the literature and wider discourse on post-war British painting and social history
Spectral-hole memory for light at the single-photon level
No full textWe demonstrate a solid-state spin-wave optical memory based on stopped light in a spectral hole. A long-lived narrow spectral hole is created by optical pumping in the inhomogeneous absorption profile of a Pr3+:Y2SiO5 crystal. Optical pulses sent through the spectral hole experience a strong reduction of their group velocity and are spatially compressed in the crystal. A short Raman pulse transfers the optical excitation to the spin state before the light pulse exits the crystal, effectively stopping the light. After a controllable delay, a second Raman pulse is sent, which leads to the emission of the stored photons. We reach storage and retrieval efficiencies for bright pulses of up to 39% in a 5-mm-long crystal. We also show that our device works at the single-photon level by storing and retrieving 3-μs-long weak coherent pulses with efficiencies up to 31%, demonstrating the most efficient spin-wave solid-state optical memory at the single-photon level so far. We reach an unconditional noise level of (9±1)×10-3 photons per pulse in a detection window of 4μs, leading to a signal-to-noise ratio of 33±4 for an average input photon number of 1, making our device promising for long-lived storage of nonclassical light.Fil: Kutluer, Kutlu. Barcelona Institute of Technology; EspañaFil: Pascual Winter, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Dajczgewand, Julian Eduardo. Université Paris Sud; Francia. Centre National de la Recherche Scientifique; FranciaFil: Ledingham, Patrick M.. Barcelona Institute of Technology; EspañaFil: Mazzera, Margherita. Barcelona Institute of Technology; EspañaFil: Chanelière, Thierry. Université Paris Sud; Francia. Centre National de la Recherche Scientifique; FranciaFil: De Riedmatten, Hugues. Barcelona Institute of Technology; Españ
Quantum storage of a photonic polarization qubit in a solid
No full textWe report on the quantum storage and retrieval of photonic polarization quantum bits onto and out of a solid state storage device. The qubits are implemented with weak coherent states at the single photon level, and are stored for a predetermined time of 500 ns in a praseodymium doped crystal with a storage and retrieval efficiency of 10%, using the atomic frequency comb scheme. We characterize the storage by using quantum state tomography, and find that the average conditional fidelity of the retrieved qubits exceeds 95% for a mean photon number μ=0.4. This is significantly higher than a classical benchmark, taking into account the Poissonian statistics and finite memory efficiency, which proves that our crystal functions as a quantum storage device for polarization qubits. These results extend the storage capabilities of solid state quantum light matter interfaces to polarization encoding, which is widely used in quantum information science.</p
Postfazione. Utopia e speranza: Bologna per Patrick Zaki
No full textThe essay elaborates on the talk the author delivered during the ceremony that took place after the liberation from prison of the UNIBO and honorary citizen of Bologna, Patrick Zaki. The essay elaborates on the following issues: the support of the university and city, the value of human rights, academic freedom, and public squares as spaces of democracy. It includes a longer part on utopia (as a literary genre and a political instrument of change) and hope, quoting academic scholars (Karl Mannheim, Ernst Bloch, Ursula Le Guin, Antonio Gramsci, Howard Zinn) and it explains the function of hope in utopia
Quantum storage of a photonic polarization qubit in a doped crystal
No full textWe report storage of photonic polarization qubits in a crystal. The average conditional fidelity of retrieved qubits exceeds 95% for a mean photon number μ = 0.4, higher than the classical benchmark proving the quantum nature of the storage.</p
Hybrid optical and electronic laser locking using slow light due to spectral holes
No full textWe report on a narrow linewidth laser diode system that is stabilized using both optical and electronic feedback to a spectral hole in cryogenic Tm:YAG. The large group delay of the spectral hole leads to a laser with very low phase noise. The laser has proved useful for quantum optics and sensing applications involving cryogenic rare-earth-ion dopants.</p
Quantum Correlations between Single Telecom Photons and a Multimode On-Demand Solid-State Quantum Memory
No full textQuantum correlations between long-lived quantum memories and telecom photons that can propagate with low loss in optical fibers are an essential resource for the realization of large-scale quantum information networks. Significant progress has been realized in this direction with atomic and solid-state systems. Here, we demonstrate quantum correlations between a telecom photon and a multimode on-demand solid state quantum memory. This is achieved by mapping a correlated single photon onto a spin collective excitation in a Pr^{3+}:Y_{2}SiO_{5} crystal for a controllable time. The stored single photons are generated by cavity-enhanced spontaneous parametric down-conversion and heralded by their partner photons at telecom wavelength. These results represent the first demonstration of a multimode on-demand solid state quantum memory for external quantum states of light. They provide an important resource for quantum repeaters and pave the way for the implementation of quantum information networks with distant solid state quantum nodes
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