Polynomial approximation of non-Gaussian unitaries by counting one photon at a time

In quantum computation with continous-variable systems, quantum advantage can only be achieved if some non-Gaussian resource is available. Yet, non-Gaussian unitary evolutions and measurements suited for computation are challenging to realize in the lab. We propose and analyze two methods to apply a polynomial approximation of any unitary operator diagonal in the amplitude quadrature representation, including non-Gaussian operators, to an unknown input state. Our protocols use as a primary non-Gaussian resource a single-photon counter. We use the fidelity of the transformation with the target one on Fock and coherent states to assess the quality of the approximate gate.Comment: 11 pages, 7 figure

Versatile engineering of multimode squeezed states by optimizing the pump spectral profile in spontaneous parametric down-conversion

We study the quantum correlations induced by spontaneous parametric down-conversion (SPDC) of a frequency comb. We derive a theoretical method to find the output state corresponding to a pump with an arbitrary spectral profile. After applying it to the relevant example of a spectrally chirped pump, we run an optimization algorithm to numerically find the pump profiles maximizing some target functions. These include the number of independently squeezed modes and the variances of nullifiers defining cluster states used in many continuous-variable quantum information protocols. To assess the advantages of pump-shaping in real experiments we take into account the physical limitations of the pulse shaper.Comment: Updated title, improved presentation and figures, added references, corrected typos. Closer to the version accepted for publicatio

Random coding for sharing bosonic quantum secrets

We consider a protocol for sharing quantum states using continuous variable systems. Specifically we introduce an encoding procedure where bosonic modes in arbitrary secret states are mixed with several ancillary squeezed modes through a passive interferometer. We derive simple conditions on the interferometer for this encoding to define a secret sharing protocol and we prove that they are satisfied by almost any interferometer. This implies that, if the interferometer is chosen uniformly at random, the probability that it may not be used to implement a quantum secret sharing protocol is zero. Furthermore, we show that the decoding operation can be obtained and implemented efficiently with a Gaussian unitary using a number of single-mode squeezers that is at most twice the number of modes of the secret, regardless of the number of players. We benchmark the quality of the reconstructed state by computing the fidelity with the secret state as a function of the input squeezing.Comment: Updated figure 1, added figure 2, closer to published versio

a lattice perspective

We examine general Gottesman-Kitaev-Preskill (GKP) codes for continuous-variable quantum error correction, including concatenated GKP codes, through the lens of lattice theory, in order to better understand the structure of this class of stabilizer codes. We derive formal bounds on code parameters, show how different decoding strategies are precisely related, propose new ways to obtain GKP codes by means of glued lattices and the tensor product of lattices and point to natural resource savings that have remained hidden in recent approaches. We present general results that we illustrate through examples taken from different classes of codes, including scaled self-dual GKP codes and the concatenated surface-GKP code

High-dimensional quantum encoding via photon-subtracted squeezed states

We introduce a high-dimensional quantum encoding based on coherent mode-dependent single-photon subtraction from multimode squeezed states. This encoding can be seen as a generalization to the case of non-zero squeezing of the standard single-photon multi-rail encoding. The advantage is that the presence of squeezing enables the use of common tools in continuous-variable quantum processing, which in turn allows to show that arbitrary $d$-level quantum states can be generated and detected via simply tuning the classical fields that gates the photon-subtraction scheme. Therefore, the scheme is suitable for mapping arbitrary classical data in quantum mechanical form. Regardless the dimension of the data set alphabet, the mapping is conditioned on the subtraction of a single photon only, making it nearly unconditional. We prove that this encoding can be used to calculate vector distances, a pivotal primitive in various quantum machine learning algorithms.Comment: 12 pages, 3 figures. Corrected typos, closer to published versio

Collagen-specific T-cell repertoire in blood and synovial fluid varies with disease activity in early rheumatoid arthritis

Type II collagen is a DR4/DR1 restricted target of self-reactive T cells that sustain rheumatoid arthritis. The aim of the present study was to analyze the T-cell receptor repertoire at the onset of and at different phases in rheumatoid arthritis. We used the CDR3 BV-BJ spectratyping to study the response to human collagen peptide 261-273 in 12 patients with DR4+ rheumatoid arthritis (six at the onset of disease and six during the course of disease) and in five healthy DR4+ relatives. The collagen-specific T-cell repertoire is quite restricted at the onset of disease, involving approximately 10 rearrangements. Within the studied collagen-specific rearrangements, nearly 75% is shared among patients. Although the size of the repertoire used by control individuals is comparable to that of patients, it is characterized by different T-cell receptors. Part of the antigen-specific T-cell repertoire is spontaneously enriched in synovial fluid. The specific T-cell repertoire in the periphery was modulated by therapy and decreased with the remission of the disease. Failure of immunoscopy to detect this repertoire was not due to suppression of collagen-driven proliferation in vitro by CD4+ CD25+ T cells. Clinical relapse of the disease was associated with the appearance of the original collagen-specific T cells. The collagen-specific T-cell receptor repertoire in peripheral blood and synovial fluid is restricted to a limited number of rearrangements in rheumatoid arthritis. The majority of the repertoire is shared between patients with early rheumatoid arthritis and it is modulated by therapy

Plasma miR-151-3p as a Candidate Diagnostic Biomarker for Head and Neck Cancer: A Cross-sectional Study within the INHANCE Consortium

Background: Identification of screening tests for the detection of head and neck cancer (HNC) at an early stage is an important strategy to improving prognosis. Our objective was to identify plasma circulating miRNAs for the diagnosis of HNC (oral and laryngeal subsites), within a multicenter International Head and Neck Cancer Epidemiology consortium. Methods: A high-throughput screening phase with 754 miRNAs was performed in plasma samples of 88 cases and 88 controls, followed by a validation phase of the differentially expressed miRNAs, identified in the screening, in samples of 396 cases and 396 controls. Comparison of the fold changes (FC) was carried out using the Wilcoxon rank-sum test and the Dunn multiple comparison test. Results: We identified miR-151-3p (FC = 1.73, P = 0.007) as differentially expressed miRNAs in the screening and validation phase. The miR-151-3p was the only overexpressed miRNA in validation sample of patients with HNC with early stage at diagnosis (FC = 1.81, P = 0.008) and it was confirmed upregulated both in smoker early-stage cases (FC = 3.52, P = 0.024) and in nonsmoker early-stage cases (FC = 1.60, P = 0.025) compared with controls. Conclusions: We identified miR-151-3p as an early marker of HNC. This miRNA was the only upregulated in patients at early stages of the disease, independently of the smoking status. Impact: The prognosis for HNC is still poor. The discovery of a new diagnostic biomarker could lead to an earlier tumor discovery and therefore to an improvement in patient prognosis

Plasma miR-151-3p as a candidate diagnostic biomarker for head and neck cancer: a cross-sectional study within the INHANCE consortium

Identification of screening tests for the detection of head and neck cancer at an early stage is an important strategy to improving prognosis. Our objective was to identify plasma circulating microRNAs for the diagnosis of head and neck cancer (oral and laryngeal subsites), within a multicenter International Head and Neck Cancer Epidemiology (INHANCE) consortium

Glutathione s-transferase gene polymorphisms in italian patients with sudden sensorineural hearing loss.

HYPOTHESIS: To investigate the association between glutathione S-transferase (GST) gene polymorphisms and sudden sensorineural hearing loss (SSNHL) in a population of consecutive Italian patients. Assuming that reactive oxygen species formation may play a role in inner ear damage, we investigated whether profiles of GSTs antioxidant enzymes M1 and T1 genotypes may be associated with the risk of SSNHL. STUDY DESIGN: A prospective study in patients with SSNHL. PATIENTS AND METHODS: We investigated 80 Italian patients with SSNHL for the frequency of GSTT1 and GSTM1 polymorphisms. Genotype distribution of all factors found in patients were compared with those of 80 healthy control subjects of the same ethnic background using chi and odds-ratio analysis. Statistical significance was accepted at a level of p < 0.05. RESULTS: In our series, the frequencies of GSTM1 and GSTT1 null genotypes did not differ from those of the control subjects. CONCLUSION: The few studies regarding genetic polymorphisms of GSTs in SSNHL are not conclusive. Further studies are needed to investigate the role of antioxidants including GSTs in SSNHL and to provide the lacking information to improve our knowledge in the field before implementing the use of genetic polymorphism in the SSNHL medicine daily practice