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We report on a quantum thermodynamic method to purify a qubit on a quantum processing unit (QPU) equipped with (nearly) identical qubits. Our starting point is a three qubit design that emulates the well-known two qubit swap engine. Similar to standard fridges, the method would allow us to cool down a qubit at the expense of heating two other qubits. A minimal modification thereof leads to a more practical three qubit design that allows for enhanced refrigeration tasks, such as increasing the purity of one qubit at the expense of decreasing the purity of the other two. The method is based on the application of properly designed quantum circuits and can therefore be run on any gate model quantum computer. We implement it on a publicly available superconducting qubit based QPU and observe a purification capability down to 200 mK. We identify gate noise as the main obstacle toward practical application for quantum computing.

Long-range interacting quantum devices provides a promising route for quantum technology applications. Here, the presence of long-range interactions is shown to enhance the performances of a quantum heat engine featuring a many-body working substance. We focus on the paradigmatic example of a Kitaev chain undergoing a quantum Otto cycle and show that a substantial thermodynamic advantage may be achieved as the range of the interactions among its constituents increases. The advantage is most significant for the realistic situation of a finite time cycle: the presence of long-range interactions reduces the non-adiabatic energy losses, by suppressing the detrimental effects of dynamically generated excitations. This effect allows mitigating the trade-off between power and efficiency, paving the way for a wide range of experimental and technological applications., New Journal of Physics, 25 (3), ISSN:1367-2630

Engineering long-range interactions in experimental platforms has been achieved with great success in a large variety of quantum systems in recent years. Inspired by this progress, we propose a generalization of the classical Hamiltonian mean-field model to fermionic particles. We study the phase diagram and thermodynamic properties of the model in the canonical ensemble for ferromagnetic interactions as a function of temperature and hopping. At zero temperature, small charge fluctuations drive the many-body system through a first order quantum phase transition from an ordered to a disordered phase at zero temperature. At higher temperatures, the fluctuation-induced phase transition remains first order initially and switches to second order only at a tricritical point. Our results offer an intriguing example of tricriticality in a quantum system with long-range couplings, which bears direct experimental relevance. The analysis is performed by exact diagonalization and mean-field theory.

Social and occupational impairments are present in the schizophrenia prodrome, and poor social functioning predicts transition to psychosis in Ultra-High Risk (UHR) individuals. We aimed to: 1) validate the Italian version of the Global Functioning: Social (GF: S) and Global Functioning: Role (GF: S) scales; 2) evaluate their association with UHR criteria. Participants were 12-21-years-old (age, mean=15.2, standard deviation=2.1, male/female ratio=117/120) nonpsychotic help-seekers, meeting (N=39) or not (N=198) UHR criteria. Inter-rater reliability was excellent for both scales, which also showed good to excellent concurrent validity, as measured by correlation with Global Assessment of Functioning (GAF) scores. Furthermore, GF:S and GF: R were able to discriminate between UHRs and non-UHRs, with UHRs having lower current scores. After adjusting for current GAF scores, only current GF:S scores independently differentiated UHR from non-UHR (OR=1.33, 95%CI: 1.02-1.75, p=0.033). Finally, UHR participants showed a steeper decrease from highest GF:S and GF: R scores in the past year to their respective current scores, but not from highest past year GAF scores to current scores. GF:S/GS: R scores were not affected by age or sex. GF:S/GF: R are useful functional level and outcome measures, having the advantage over the GAF to not confound functioning with symptom severity. Additionally, the GF:S may be helpful in identifying UHR individuals.

We study the maximal amount of energy that can be extracted from a finite quantum system by means of projective measurements. For this quantity we coin the expression "metrotropy" $\mathcal{M}$, in analogy with "ergotropy" $\mathcal{W}$, which is the maximal amount of energy that can be extracted by means of unitary operations. The study is restricted to the case when the system is initially in a stationary state, and therefore the ergotropy is achieved by means of a permutation of the energy eigenstates. We show that i) the metrotropy is achieved by means of an even combination of the identity and an involution permutation; ii) it is $\mathcal{M}\leq\mathcal{W}/2$, with the bound being saturated when the permutation that achieves the ergotropy is an involution., Comment: 12 pages, 3 figures. Contribution to the special issue of JSTAT "New Trends in Nonequilibrium Statistical Mechanics: Classical and Quantum Systems - nesmcq18". v2 = published version

According to Clausius formulation of the second law of thermodynamics, for any thermal machine withdrawing heats $Q_{1,2}$ from two heat reservoirs at temperatures $T_{1,2}$, it holds $Q_1/T_1+Q_2/T_2 \leq 0$. Combined with the observation that the quantity $Q_1+Q_2$ is the work $W$ done by the system, that inequality tells that only 4 possible operation modes are possible for the thermal machine, namely heat engine [E], refrigerator [R], thermal accelerator [A] and heater [H]. We illustrate their emergence in the finite time operation of a quantum Otto engine realised with a single qubit. We first focus on the ideal case when isothermal and thermally-insulated strokes are well separated, and give general results as well as results pertaining to the specific finite-time Landau-Zener dynamics. We then present realistic results pertaining to the solid-state experimental implementation proposed by Karimi and Pekola [Phys. Rev. B \textbf{94} (2016) 184503]. That device is non-adiabatic both in the quantum mechanical sense and in the thermodynamical sense. Oscillations in the power extracted from the baths due to coherent LZ tunnelling at too low temperatures are observed that might hinder the robustness of the operation of the device against experimental noise on the control parameters., Comment: 10 pages, 7 figures

Invasiveness of quantum measurements is a genuinely quantum mechanical feature that is not necessarily detrimental: Here we show how quantum measurements can be used to fuel a cooling engine. We illustrate quantum measurement cooling (QMC) by means of a prototypical two-stroke two-qubit engine which interacts with a measurement apparatus and two heat reservoirs at different temperatures. We show that feedback control is not necessary for operation while entanglement must be present in the measurement projectors. We quantify the probability that QMC occurs when the measurement basis is chosen randomly, and find that it can be very large as compared to the probability of extracting energy (heat engine operation), while remaining always smaller than the most useless operation, namely dumping heat in both baths. These results show that QMC can be very robust to experimental noise. A possible low-temperature solid-state implementation that integrates circuit QED technology with circuit quantum thermodynamics technology is presented., Comment: 18 pages, 4 figures

Background Current early screeners for psychosis-risk states have still to prove ability in identifying at-risk individuals. Among screeners, the 92-item Prodromal Questionnaire (PQ-92) is often used. We aimed to assess the validity of its Italian translation in a large Italian adolescent and young adult help-seeking sample. Methods We included all individuals aged 12–36 years seeking help at psychiatric mental health services in a large semirural Roman area (534,600 population) who accepted to participate. Participants completed the Italian version of the PQ-92 and were subsequently assessed with the Structured Interview of Prodromal/Psychosis-Risk Syndromes (SIPS). We examined diagnostic accuracy (sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios) and content, concurrent, and convergent validity between PQ-92 and SIPS using Cronbach's alpha , Cohen's kappa , and Spearman's rho , respectively. We tested the validity of adopted cut-offs through Receiver Operating Characteristic (ROC) curves plotted against SIPS diagnoses and the instrument's factor-structure through Principal Component Analysis. Results PQ-92 showed high internal consistency, acceptable diagnostic accuracy and concurrent validity, and excellent convergent validity. ROC analyses pointed to scores of 18 on the Positive subscale and 36 on the total PQ-92 as best cut-offs. The Scree-test identified a four-factor solution as fitting best. Conclusions Psychometric properties of Italian PQ-92 were satisfactory. Optimal cut-offs were confirmed at ≥ 18 on the positive subscale, but at ≥ 36 on the total scale was able to identify more SIPS-positive cases.

A personality trait that often elicits poor and uneasy interpersonal relationships is interpersonal sensitivity. The aim of the present study was to explore the relationship between interpersonal sensitivity and psychosocial functioning in individuals at ultra-high risk for psychosis as compared to help-seeking individuals who screened negative for an ultra-high risk of psychosis. A total sample of 147 adolescents and young adult who were help seeking for emerging mental health problems participated in the study. The sample was divided into two groups: 39 individuals who met criteria for an ultra-high-risk mental state (UHR), and 108 (NS). The whole sample completed the Interpersonal Sensitivity Measure (IPSM) and the Global Functioning: Social and Role Scale (GF:SS; GF:RS). Mediation analysis was used to explore whether attenuated negative symptoms mediated the relationship between interpersonal sensitivity and social functioning. Individuals with UHR state showed higher IPSM scores and lower GF:SS and GF:RS scores than NS participants. A statistically negative significant correlation between two IPSM subscales (Interpersonal Awareness and Timidity) and GF:SS was found in both groups. Our results also suggest that the relationship between the aforementioned aspects of interpersonal sensitivity and social functioning was not mediated by negative prodromal symptoms. This study suggests that some aspects of interpersonal sensitivity were associated with low level of social functioning. Assessing and treating interpersonal sensitivity may be a promising therapeutic target to improve social functioning in young help-seeking individuals.

Objective Self-rated attenuated psychotic-like experiences (APLEs) are increasingly used to screen for ultra-high-risk (UHR) across all ages. However, self-rated psychotic-like experiences (PLEs), in particular perception-related ones, were more frequent in children and adolescents, in which they possessed less clinical significance. We therefore explored the prevalence of different factors of APLEs in help-seeking adolescents, and their relationship with age, functioning and psychopathology. Method As a part of the “Liberiamo il Futuro” project, help-seeking adolescents (N = 171; 11–18 years, 53% male) were screened with the 92-item Prodromal Questionnaire (PQ-92). A factor analysis was performed on the PQ-92 positive items (i.e., APLEs) to identify different APLE-factors. These were assessed for their association with age, functioning and psychopathology using regression analyses. Results APLEs were very common in help-seeking adolescents, and formed four factors: “Conceptual Disorganization and Suspiciousness”, “Perceptual Abnormalities”, “Bizarre Experiences”, and “Magical Ideation”. Associations with age and functioning but not psychopathology were found for “Perceptual Abnormalities” that was significantly more severe in 11–12-year-olds, while “Conceptual Disorganization and Suspiciousness” was significantly related to psychopathology. Conclusion In line with findings on PLEs, prevalence and clinical significance of APLEs, especially perception-related ones, might depend on age and thus neurodevelopmental stage, and may fall within the normal spectrum of experience during childhood. This should be considered when screening for UHR status in younger age groups.

Background Interpersonal sensitivity is a personality trait that describes as excessive awareness of both the behaviour and feelings of others. High interpersonal sensitivity has been associated with the development and maintenance of mental health problems. This study aimed to examine whether the Italian version of the interpersonal sensitivity measure (IPSM) has good internal consistence and convergent validity. Methods Validity was established on a sample of 153 Italian adolescents and young adult help seekers for several psychological problems. These subjects were divided in two groups – depressive spectrum disorder group ( n =42) and other diagnosis group ( n =111) – according to Structured Clinical Interview (SCID-I) for DSM-IV and Kiddie-Sads-Present and Lifetime Version (K-SADS-PL). For convergent validity, we studied the correlation between total and each subscale IPSM scores and the General Symptoms (included depressive and dysphoric symptoms) of Prodromal Questionnaire. Results The internal consistency were adequate and comparable to the original Boyce and Parker study. The validity was good, as indicated by both the convergent validity analysis and the depressive spectrum disorder group and other diagnosis group comparison. Limitations The absence of another scale measuring interpersonal sensitivity to assess the construct validity of IPSM; the clinical heterogeneity of the sample; the absence of test re-test reliability of the instrument. Conclusions Analysis of the results of internal consistency and convergent validity of the IPSM indicates that this version translated into Italian is valid and reliable.

Background: Craving for alcohol is associated with abnormal activation in the dorsolateral prefrontal cortex. Deep transcranial magnetic stimulation (dTMS) has shown promise in the treatment of depression. There are few treatment options for treatment-resistant dysthymic disorder comorbid with alcohol use disorder. Objective: To investigate the possible anticraving efficacy of bilateral dorsolateral prefrontal cortex high-frequency dTMS in 3 patients with comorbid long-term DSM-IV-TR dysthymic disorder and alcohol use disorder. Method: Three patients with alcohol use disorder with dysthymic disorder in their detoxification phase (abstaining for > 1 month) underwent twenty 20-minute sessions of 20 Hz dTMS over the dorsolateral prefrontal cortex over 28 days between 2011 and 2012. Alcohol craving was rated with the Obsessive Compulsive Drinking Scale and depressive symptoms with the Hamilton Depression Rating Scale. Results: All 3 patients responded unsatisfactorily to initial intravenous antidepressant and antianxiety combinations but responded after 10 dTMS sessions, improving on both anxiety-depressive symptoms and craving. This improvement enabled us to reduce antidepressant dosages after dTMS cycle completion. Discussion: High-frequency bilateral dorsolateral prefrontal cortex dTMS with left prevalence was found to produce significant anticraving effects in alcohol use disorder comorbid with dysthymic disorder. The potential of dTMS for reducing craving in patients with substance use disorder deserves to be further investigated.

To evaluate the efficacy of olanzapine in patients in their manic/mixed phase with or without comorbidity with substance abuse/dependence disorder.In this observational, controlled, prospective study, 60 patients with a DSM-IV-TR diagnosis of bipolar disorder, manic/mixed episode (30 patients with and 30 patient without comorbidity with a substance abuse/dependence disorder) were treated with olanzapine, evaluated at discharge, and followed-up for 8 weeks. Efficacy of olanzapine was assessed by comparing the proportion of responders (an at least 50% drop in Young Mania Rating Scale [YMRS] score from baseline) and remitters (YMRS ≤ 12 and Hamilton Depression Rating Scale [HAM-D] ≤ 8) in both groups. Craving and days of abuse/use were assessed with Visual Analogue Scale (VAS) and Time-line Follow-Back (TLFB), respectively.Differences in response and remission percentages were statistically not significant at discharge and during follow-up. A reduction of days of abuse has been observed in the drug-abuse group, while craving was only slightly decreased.These results suggest that olanzapine is effective in both groups and its efficacy in reducing the days of abuse appears to be independent from its action on craving.