Quantum Work Capacitances

The possibility of using quantum effects to speed up the charging processes of batteries have been vastly investigated. In order to traslate these ideas into working devices it is however crucial to assess the stability of the storage phase in the quantum battery elements when they are in contact with environmental noise. In this work we formalize this problem introducing a series of operationally well defined figures of merit (the work capacitances and the Maximal Asymptotic Work/Energy Ratios) which gauge the highest efficiency one can attain in recovering useful energy from quantum battery models that are formed by large collections of identical and independent elements (quantum cells or q-cells). Explicit evaluations of such quantities are presented for the case where the energy storing system undergoes through dephasing and depolarizing noise.Comment: 15 pages, 5 figure

Work extraction processes from noisy quantum batteries: the role of non local resources

We demonstrate an asymmetry between the beneficial effects one can obtain using non-local operations and non-local states to mitigate the detrimental effects of environmental noise in the work extraction from quantum battery models. Specifically, we show that using non-local recovery operations after the noise action can in general increase the amount of work one can recover from the battery even with separable (i.e. non entangled) input states. On the contrary, employing entangled input states with local recovery operations will not generally improve the battery performances.Comment: 11 pages, 3 figures, it matches the journal versio

Quantum work extraction efficiency for noisy quantum batteries: the role of coherence

Quantum work capacitances and maximal asymptotic work/energy ratios are figures of merit characterizing the robustness against noise of work extraction processes in quantum batteries formed by collections of quantum systems. In this paper we establish a direct connection between these functionals and, exploiting this result, we analyze different types of noise models mimicking self-discharging, thermalization and dephasing effects. In this context we show that input quantum coherence can significantly improve the storage performance of noisy quantum batteries and that the maximum output ergotropy is not always achieved by the maximum available input energy.Comment: 16 pages, 8 figure

Quantum Algorithms for the computation of quantum thermal averages at work

Recently, a variety of quantum algorithms have been devised to estimate thermal averages on a genuine quantum processor. In this paper, we consider the practical implementation of the so-called Quantum-Quantum Metropolis algorithm. As a testbed for this purpose, we simulate a basic system of three frustrated quantum spins and discuss its systematics, also in comparison with the Quantum Metropolis Sampling algorithm.Comment: 12 pages, 9 figure

Metastatic group 3 medulloblastoma is driven by PRUNE1 targeting NME1-TGF-β-OTX2-SNAIL via PTEN inhibition.

Genetic modifications during development of paediatric groups 3 and 4 medulloblastoma are responsible for their highly metastatic properties and poor patient survival rates. PRUNE1 is highly expressed in metastatic medulloblastoma group 3, which is characterized by TGF-β signalling activation, c-MYC amplification, and OTX2 expression. We describe the process of activation of the PRUNE1 signalling pathway that includes its binding to NME1, TGF-β activation, OTX2 upregulation, SNAIL (SNAI1) upregulation, and PTEN inhibition. The newly identified small molecule pyrimido-pyrimidine derivative AA7.1 enhances PRUNE1 degradation, inhibits this activation network, and augments PTEN expression. Both AA7.1 and a competitive permeable peptide that impairs PRUNE1/NME1 complex formation, impair tumour growth and metastatic dissemination in orthotopic xenograft models with a metastatic medulloblastoma group 3 cell line (D425-Med cells). Using whole exome sequencing technology in metastatic medulloblastoma primary tumour cells, we also define 23 common 'non-synonymous homozygous' deleterious gene variants as part of the protein molecular network of relevance for metastatic processes. This PRUNE1/TGF-β/OTX2/PTEN axis, together with the medulloblastoma-driver mutations, is of relevance for future rational and targeted therapies for metastatic medulloblastoma group 3

Different phases of interacting fermions in low dimensional lattices with synthetic gauge fields

The aim of my master thesis is the study of a strongly anisotropic fermionic ladder system through numerical variational methods. The system considered in our work consists in a quasi-1D lattice filled with spinless fermions, which is very long on the x direction (real dimension), but with only few sites on the y direction (synthetic dimension). The motivation for studying this model arises from various ultacold-atom experiments, in which scientists have been able to realize through magneto-optical confining techniques these kind of lattices pierced by a synthetic gauge field. Since our lattice is not strictly unidimensional, it is possible to introduce a synthetic gauge field. The presence of a synthetic magnetic flux allows us to study geometric frustration effects depending both on the magnitude of the field and on the density of particles in the chain. These effects causes interesting outcomes such as fermionic localization. This kind of structure can be encoded in a 1D system with an effective local hamiltonian dimension 2^n where n is the number of sites on the synthetic dimension. It was proven that through the presence of nontrivial complex phases in the hopping term along the y axis, which mimic the effect of a magnetic field, the behavior of this system shows similarities with the physics of Quantum Hall Effect (QHE). Strongly correlated systems are extremely hard, if not impossible, to solve analytically. Moreover, in our case, perturbation techniques typically fail, because the ratio between the magnitude of the interacting terms and that of the hopping term is r ≥ 1, in fact, if there were no interactions, the model would be exactly solvable by mapping it in a free fermions system. However an interaction term is necessary to unveil a much richer physics, which can encompass peculiar phenomena including fermionic crystallization at fractional density of particles. So our purpose is to understand the properties of this model in the strongly interacting regime via density matrix renormalization group (DMRG) simulations if an interaction Hubbard term is added to the Hamiltonian. This will be achieved by finding a transition between a crystalline and a liquid phase[3] in dependence of the Hubbard coupling. The analysis is performed with a matrix product states (MPS) algorithm, which is known to be the most accurate method to deal with 1D quantum chains. MPS algorithm is a more flexible yet equally powerful transposition of DMRG. This approach enables to easily measure quantities like local magnetization, local density, correlation functions and bipartite von Neumann Entropy. In conclusion the results of this study will be useful to attain a better understanding of the possible fermionic phases in low dimensional structures with the presence of a magnetic gauge field. Our investigation on the quantum phase diagram of the system has shed light on interesting phenomena. We work both on the 2-leg and on the 3-leg ladder configuration, the former has only two sites on the synthetic dimension, the latter has three sites on this dimension. Although the difference seems irrelevant, the two configurations appear to behave very differently. This model is SU(N)-symmetric where N is the number of legs chosen, because we work with periodic boundary conditions on the synthetic dimension. Notice that also the interaction terms that we will consider respect this group of symmetry. An important quantity to take in account is the filling number ν which is defined as ν=n/[(M + 1)φ] where n is the density of particles along the real direction, M depends on the kind of system, M = 1 for the 2-leg and M = 2 for the 3-leg, and φ is the parameter of the complex phase that simulate the magnetic field. A way to identify the phase of our system is to measure the bipartite von Neumann entropy, or entanglement entropy: if the system is in a pure state and it is split in two parts, the entanglement entropy is defined as the von Neumann entropy of one of the two subsystems. This quantity allows to discriminate a gapped system, in which entanglement entropy is a flat function of the site, from a gapless one, where the entanglement entropy has a bell-shape. By the variation of both ν and φ the MPS algorithm permits us to observe either a crystalline ordered phase, where the local density of fermions is periodic, or a liquid disordered one, in which the local density of particles is flat. In the 2-leg lattice we see an ordered phase only when φ = 1/2 and ν ≥ 1/2 if U is sufficiently large, while for ν < 1/2 a crystalline phase appears only if a repulsive nearest neighbors interaction is switched on. The order parameter for the phase transition is the charge gap ∆E which is defined as ∆E = E(k+1)+E(k−1)−2E(k) where E(k) is the energy of the system with k particles. In contrast in the 3-leg lattice crystal phases arise even if φ ̸= 1/2, and an ordered phase is stabilized for proper U in the case ν = 1/3. We also notice a peculiar behavior of the correlations of the magnetization in our chain, because they appear to be periodic even under the transition point, so the system shows magnetic order and structural disorder at the same time, both in the 2-leg and in the 3-leg case

Clinical evaluation of near-infrared light transillumination (NIRT) as an interproximal caries detection tool in a large sample of patients in a private practice

Background: A study has been carried out in order to evaluate in vivo the diagnostic performance of near-infrared light transillumination (NIRT) compared to digital radiographic examination (RE) in the detection of class II carious lesions. Methods: A total of 114 patients were included, and 2957 proximal surfaces were considered. Surfaces were imaged by means of NIRT and radiographed with a photostimulable phosphor system. NIRT and radiographic images were observed by two blinded operators. Their diagnoses were compared with those made while visiting the patients, when visual-tactile, radiographic and NIRT data were matched by expert operators to obtain the reference diagnoses. Sensitivity, specificity and inter-observer consistency were calculated. Results: Throughout the visits, 395 caries were detected. When investigating without clinical information and in a blind manner, RE performed significantly better than NIRT regarding sensitivity analysis (0.591 vs. 0.456, p<0.001), and NIRT performed significantly better than RE regarding specificity analysis (0.980 vs 0.933, p<0.001). However, NIRT showed sensitivity similar to RE when only enamel caries were concerned. With regard to the agreement between the two observers, NIRT performed significantly better than RE (0.901 for RE analysis, 0.989 for NIRT analysis, P<0.001). A high probability of false positives for enamel caries (95% from 0.699 to 0.791) was observed in RE. NIRT was very likely to detect and correct the erroneous positive diagnosis of enamel carious lesions obtained using RE (95% CI for probability from 0.938 to 0.979). Conclusions: NIRT should be used in caries diagnosis in combination with radiographic images. In fact, NIRT can help to correct a false positive diagnosis of enamel caries. Furthermore, NIRT could be used to detect caries in patients for whom non-urgent radiographic exposition is contraindicated and to monitor enamel caries in medically treated patients. Finally, thanks to its three-dimensional images, NIRT can aid in detecting small caries when performing minorly invasive restorative procedures