Quantum state and mode profile tomography by the overlap

VS acknowledge support from the National Council for Scientific and Technological Development (CNPq) of Brazil, grant 304129/2015-1, and by the São Paulo Research Foundation (FAPESP), grant 2015/23296-8. DM acknowledge support from the EUproject Horizon-2020 SUPERTWIN id.686731, the National Academy of Sciences of Belarus program ‘Convergence’ and FAPESP grant 2014/21188-0. NK acknowledges the support from the Scottish Universities Physics Alliance (SUPA) and from the International Max Planck Partnership (IMPP) with Scottish Universities. JT and CS acknowledge support from European Union Grant No. 665148 (QCUMbER). TB acknowledges support from theDFG under TRR 142.Any measurement scheme involving interference of quantum states of the electromagnetic field necessarily mixes information about the spatiotemporal structure of these fields and quantum states in the recorded data. Weshow that in this case, a trade-off is possible between extracting information about the quantum states and the structure of the underlying fields, with the modal overlap being either a goal or a convenient tool of the reconstruction. Weshow that varying quantum states in a controlled way allows one to infer temporal profiles of modes. Vice versa, for the known quantum state of the probe and controlled variable overlap, one can infer the quantum state of the signal. We demonstrate this trade-off. by performing an experiment using the simplest on-off detection in an unbalanced weak homodyning scheme. For the single-mode case, we demonstrate experimentally inference of the overlap and a few-photon signal state. Moreover, we show theoretically that the same single-detector scheme is sufficient even for arbitrary multi-mode fields.Publisher PDFPeer reviewe

Extracting the physical sector of quantum states

The physical nature of any quantum source guarantees the existence of an effective Hilbert space of finite dimension, the physical sector, in which its state is completely characterized with arbitrarily high accuracy. The extraction of this sector is essential for state tomography. We show that the physical sector of a state, defined in some pre-chosen basis, can be systematically retrieved with a procedure using only data collected from a set of commuting quantum measurement outcomes, with no other assumptions about the source. We demonstrate the versatility and efficiency of the physical-sector extraction by applying it to simulated and experimental data for quantum light sources, as well as quantum systems of finite dimensions

Tdrd6 is required for spermiogenesis, chromatoid body architecture, and regulation of miRNA expression

BACKGROUND: Chromatoid bodies (CBs) are characteristic spermatid organelles, which were suggested to function in RNA storage and small RNA processing but whose functions remain largely unknown. CB components include Mili, Miwi, and Tudor domain proteins such as Tdrd6, whose contribution to CB structure and function is elusive. RESULTS: We determined gametogenesis stage- and male-specific expression and localization of Tdrd6, identified a C-terminally truncated form as predominant after meiosis I, and demonstrated direct physical interaction of Tdrd6 with the CB components Mili and Miwi. Development from round into elongated spermatids is abrogated in Tdrd6(-/-) mice. Their round spermatids bear "ghost" CBs, whose architecture is greatly disrupted. Mael, Miwi, and Mvh do not localize to the Tdrd6-deficient CBs, but retrotransposons are not significantly activated. However, more than 50 miRNAs are more abundant in Tdrd6(-/-) testes, as are exemplary pre- and pri-miRNAs. CONCLUSION: We conclude that Tdrd6 is essential for spermiogenesis, for CB structure, and for proper mature and precursor miRNA expression

Extracting the physical sector of quantum states

The physical nature of any quantum source guarantees the existence of an effective Hilbert space of finite dimension, the physical sector, in which its state is completely characterized with arbitrarily high accuracy. The extraction of this sector is essential for state tomography. We show that the physical sector of a state, defined in some pre-chosen basis, can be systematically retrieved with a procedure using only data collected from a set of commuting quantum measurement outcomes, with no other assumptions about the source. We demonstrate the versatility and efficiency of the physical-sector extraction by applying it to simulated and experimental data for quantum light sources, as well as quantum systems of finite dimensions.Comment: Comments most welcome