49 research outputs found
High dimensional measurement device independent quantum key distribution on two dimensional subspaces
Quantum key distribution (QKD) provides ultimate cryptographic security based
on the laws of quantum mechanics. For point-to-point QKD protocols, the
security of the generated key is compromised by detector side channel attacks.
This problem can be solved with measurement device independent QKD (mdi-QKD).
However, mdi-QKD has shown limited performances in terms of the secret key
generation rate, due to post-selection in the Bell measurements. We show that
high dimensional (Hi-D) encoding (qudits) improves the performance of current
mdi-QKD implementations. The scheme is proven to be unconditionally secure even
for weak coherent pulses with decoy states, while the secret key rate is
derived in the single photon case. Our analysis includes phase errors,
imperfect sources and dark counts to mimic real systems. Compared to the
standard bidimensional case, we show an improvement in the key generation rate.Comment: 6 pages, 3 figure
Quantum nondemolition measurement of mechanical motion quanta
The fields of opto- and electromechanics have facilitated numerous advances
in the areas of precision measurement and sensing, ultimately driving the
studies of mechanical systems into the quantum regime. To date, however, the
quantization of the mechanical motion and the associated quantum jumps between
phonon states remains elusive. For optomechanical systems, the coupling to the
environment was shown to preclude the detection of the mechanical mode
occupation, unless strong single photon optomechanical coupling is achieved.
Here, we propose and analyse an electromechanical setup, which allows to
overcome this limitation and resolve the energy levels of a mechanical
oscillator. We find that the heating of the membrane, caused by the interaction
with the environment and unwanted couplings, can be suppressed for carefully
designed electromechanical systems. The results suggest that phonon number
measurement is within reach for modern electromechanical setups.Comment: 8 pages, 5 figures plus 24 pages, 11 figures supplemental materia
Fast storage of photons in cavity-assisted quantum memories
Ideal photonic quantum memories can store arbitrary pulses of light with unit
efficiency. This requires operating in the adiabatic regime, where pulses have
a duration much longer than the bandwidth of the memory. In the non-adiabatic
regime of short pulses, memories are therefore imperfect, and information is
always lost. We theoretically investigate the bandwidth limitations for setups
based on individual atoms, or ensembles thereof, confined inside optical
cavities. We identify an effective strategy for optimizing the efficiencies of
the storage and retrieval process regardless of the duration of the pulses. Our
protocol is derived almost completely analytically and attains efficiencies
better than or comparable to those obtained by numerical optimization.
Furthermore, our results provide an improved understanding of the performance
of quantum memories in several regimes. When considering pulses defined on an
infinite time interval, the shapes can be divided into two categories,
depending on their asymptotic behaviours. If the intensity of the pulse
increases with time slower than or as an exponential function, then the storage
efficiency is only limited by the pulse width. For pulses defined on a finite
interval, on the other hand, the efficiency is determined by the shape at the
beginning of the storage or, correspondingly, at the end of the retrieval
process.Comment: 21 pages, 8 figures, all kinds of feedback welcom
Sexual Functioning and Opioid Maintenance Treatment in Women. Results From a Large Multicentre Study
Opioid maintenance treatment (OMT) is the most widespread therapy for both females and males opioid addicts. While many studies have evaluated the OMT impact on men’s sexuality, the data collected about the change in women’s sexual functioning is still limited despite the fact that it is now well-known that opioids - both endogenous and exogenous - affect the endocrine system and play an important role in sexual functioning. The present study aims to determine how OMT with buprenorphine (BUP) or methadone (MTD) affects sexual health in women; examining also any possible emerging correlation between sexual dysfunction (SD), type of opioid and patients’ mental health. This multi-center study case recruited 258 female volunteers attending Italian public Addiction Outpatients Centers that were stabilized with OMT for at least 3 months. SD was assessed with the Arizona Sexual Experience Scale. The twelve-item General Health Questionnaire was used to assess participants’ mental health conditions. The results show that 56.6% of women receiving OMT for at least 3 months presented SD without significant differences between MTD e BUP groups. The majority of the subjects with SD have a poorer quality of intimate relationships and worse mental health than the average. To the best of our knowledge, the present study is the largest report on the presence of SDs in women as a side effects of MTD and BUP used in OMT. Since SDs cause difficulties in intimate relationships, lower patients’ quality of life and interfere with OMT beneficial outcomes, we recommend that women undertaking an opioid therapy have routine screening for SD and we highlight the importance to better examine opioid-endocrine interactions in future studies in order to provide alternative potential treatments such as the choice of opioid, opioid dose reduction and hormone supplementation
Concetti e categorie semantiche. Un'ipotesi genetica
Il presente lavoro si colloca nell'alveo delle teorie rappresentazionalistiche della mente e indaga la costituzione delle rappresentazioni semantiche. Una prima parte del lavoro opera un'indagine critico-comparativa tesa a chiarificare l'uso di temini quali rappresentazione, concetto e significato in riferimento alle teorie di Putnam e Jackendoff, per poi passare a una discussione della costituzione del riferimento. Qui viene discussa criticamente la famiglia di teorie del riferimento fondate sul cosiddetto feature-based approach. Questa analisi porta alla problematizzazione della tipologia di informazione impiegata dal sistema cognitivo per la gestione dei riferimenti, e viene avanzata l'ipotesi, con esplicito riferimento alla fenomenologia genetica di matrice husserliana, per cui il sistema cognitivo utilizza nella sintesi rappresentazionale tutta l'informazione disponibile, esplicita ed implicita. Viene così avanzata nell'ultima parte una proposta teorica concernente il ruolo dell'informazione somatica nella costituzione delle rappresentazioni semantiche di base, legata alle tipologie di movimento proprie del "corpo vivo" con cui il sistema cognitivo è in continuo rapporto e di cui è espressione