Critical parametric quantum sensing

Critical quantum systems are a promising resource for quantum metrology applications, due to the diverging susceptibility developed in proximity of phase transitions. Here, we assess the metrological power of parametric Kerr resonators undergoing driven-dissipative phase transitions. We fully characterize the quantum Fisher information for frequency estimation, and the Helstrom bound for frequency discrimination. By going beyond the asymptotic regime, we show that the Heisenberg precision can be achieved with experimentally reachable parameters. We design protocols that exploit the critical behavior of nonlinear resonators to enhance the precision of quantum magnetometers and the fidelity of superconducting qubit readout.Comment: 6 pages + Supplemental Material, 4 figure

Revealing higher-order light and matter energy exchanges using quantum trajectories in ultrastrong coupling

The dynamics of open quantum systems is often modeled using master equations, which describe the expected outcome of an experiment (i.e., the average over many realizations of the same dynamics). Quantum trajectories, instead, model the outcome of ideal single experiments - the "clicks"of a perfect detector due to, e.g., spontaneous emission. The correct description of quantum jumps, which are related to random events characterizing a sudden change in the wave function of an open quantum system, is pivotal to the definition of quantum trajectories. In this article, we extend the formalism of quantum trajectories to open quantum systems with ultrastrong coupling (USC) between light and matter by properly defining jump operators in this regime. In such systems, exotic higher-order quantum-state and energy transfer can take place without conserving the total number of excitations in the system. The emitted field of such USC systems bears signatures of these higher-order processes, and significantly differs from similar processes at lower coupling strengths. Notably, the emission statistics must be taken at a single quantum trajectory level, since the signatures of these processes are washed out by the "averaging"of a master equation. We analyze the impact of the chosen unraveling (i.e., how one collects the output field of the system) for the quantum trajectories and show that these effects of the higher-order USC processes can be revealed in experiments by constructing histograms of detected quantum jumps. We illustrate these ideas by analyzing the excitation of two atoms by a single photon [Garziano, Phys. Rev. Lett. 117, 043601 (2016)0031-900710.1103/PhysRevLett.117.043601]. For example, quantum trajectories reveal that keeping track of the quantum jumps from the atoms allows one to reconstruct both the oscillations between one photon and two atoms as well as emerging Rabi oscillations between the two atoms

Exceptional Photon Blockade

Exceptional points (EPs) are special degeneracies in non-Hermitian systems at which both eigenvalues and their corresponding eigenvectors simultaneously coalesce. Despite numerous EP-enabled novel phenomena and applications have been revealed in classical optics, purely quantum EP effects, especially peculiar features of quantum correlations at EPs, has been elusive. Here, for a nonlinear resonator, we show that EPs can lead to up to 4 orders of magnitude difference in optical second-order quantum correlations. As a result, single-photon blockade emerges when the system is at an EP while photon-induced tunneling occurs when the system is far from EPs. Moreover, two-photon blockade can also appear by tuning the system around EPs. Our findings pave the way towards devising exotic quantum EP devices and, on a more fundamental level, shed new light on the effects of non-Hermitian degeneracies on quantum fluctuations and quantum states of photons.Comment: 8+26 pages, 3+8 figures, 3 table

Phenylthiourea Specifically Reduces Zebrafish Eye Size

Phenylthiourea (PTU) is commonly used for inhibiting melanization of zebrafish embryos. In this study, the standard treatment with 0.2 mM PTU was demonstrated to specifically reduce eye size in larval fish starting at three days post-fertilization. This effect is likely the result of a reduction in retinal and lens size of PTU-treated eyes and is not related to melanization inhibition. This is because the eye size of tyr, a genetic mutant of tyrosinase whose activity is inhibited in PTU treatment, was not reduced. As PTU contains a thiocarbamide group which is presented in many goitrogens, suppressing thyroid hormone production is a possible mechanism by which PTU treatment may reduce eye size. Despite the fact that thyroxine level was found to be reduced in PTU-treated larvae, thyroid hormone supplements did not rescue the eye size reduction. Instead, treating embryos with six goitrogens, including inhibitors of thyroid peroxidase (TPO) and sodium-iodide symporter (NIS), suggested an alternative possibility. Specifically, three TPO inhibitors, including those that do not possess thiocarbamide, specifically reduced eye size; whereas none of the NIS inhibitors could elicit this effect. These observations indicate that TPO inhibition rather than a general suppression of thyroid hormone synthesis is likely the underlying cause of PTU-induced eye size reduction. Furthermore, the tissue-specific effect of PTU treatment might be mediated by an eye-specific TPO expression. Compared with treatment with other tyrosinase inhibitors or bleaching to remove melanization, PTU treatment remains the most effective approach. Thus, one should use caution when interpreting results that are obtained from PTU-treated embryos

Pennebaker, D.A.

Scheda bio-filmografico-bibliografic

Altre x-roads. Modi dell'espressivit\ue0 afroamericana. Jazz, cinema, letteratura, storytelling, performance

Altre x-roads. Modi dell\u2019espressivit\ue0 afroamericana opera una ricognizione su alcuni aspetti dell\u2019immaginario del jazz che, integrato alla Black Music nel suo complesso, si colloca bene al centro della cultura popolare occidentale, cortocircuitando musica, letteratura, cinema, storytelling, performance. Il volume accosta il jazz da prospettive diverse, offrendo una saggistica riccamente stratificata e densa di rimandi intertestuali. Indaga questioni che innervano l\u2019estetica afroamericana alle prese con la sfera musicale e mette in luce pratiche comunicative, sfumature dell\u2019identit\ue0 nera, la \u201cmessa in immagine\u201d del jazz per gli schermi del cinema e della televisione, i rapporti tra performance, innovazione e tradizione, cos\uec come talune consuetudini dello storytelling o del signifying. Le tre sezioni che lo compongono (Indagini, Affetti, Coriandoli) mettono in fila saggi che affrontano, rispettivamente, una ricognizione sugli orizzonti pi\uf9 ampi della cultura del jazz, il recupero affettivo di tre grandissime figure di questa musica (Charlie Parker, Charles Mingus, Billie Holiday) e la ricapitolazione di una serie di interventi che aprono anche ad altre musiche del mondo come il klezmer

"Amplificare lo schiocco e il sibilo dell'universo": la voce della radio, la sua grana sonora, la sua aura mediatica

Numero monografico "Il testo, la voce", a cura di Giorgio Rimond

"In the Shadow of No Towers": l'arte grafica di Art Spiegelman come contro-narrazione di 9/11

Il saggio su "In the Shadow of No Towers" di Art Spiegelman contestualizza l'opera all'interno della produzione di arte grafica (non solo fumetto, dunque) dell'autore, soffermandosi in particolare sul senso profondo di contro-narrazione dell'11 settembre (2001: l'attentato alle torri gemelle del World Trade Center) che quel lavoro specifico pare incarnare. "In the Shadow of No Towers" viene letto in continuit\ue0 con il precedente "Maus", il famoso e pluripremiato "graphic novel" di Spiegelman che interviene sulla narrazione della Shoah. Nel saggio si mostra come l'urgenza affettiva e politica di una reazione all'attentato venga trasformata, se non proprio sublimata, per tramite di una precisa scelta di campo nell'ambito della propria arte, rivisitata alla luce di una rilettura della storia del fumetto americano degli esordi. La personale elaborazione del lutto dell'autore -- in qualche modo direttamente coinvolto nell'evento -- attraverso l'atto di elaborazione creativa del fumetto colloca idealmente Spiegelman tra i potenziali terapeuti del trauma di 9/11