Fundamental Limits to Coherent Photon Generation with Solid-State Atomlike Transitions

Coherent generation of indistinguishable single photons is crucial for many quantum communication and processing protocols. Solid-state realizations of two-level atomic transitions or three-level spin-$\Lambda$ systems offer significant advantages over their atomic counterparts for this purpose, albeit decoherence can arise due to environmental couplings. One popular approach to mitigate dephasing is to operate in the weak excitation limit, where excited state population is minimal and coherently scattered photons dominate over incoherent emission. Here we probe the coherence of photons produced using two-level and spin-$\Lambda$ solid-state systems. We observe that the coupling of the atomic-like transitions to the vibronic transitions of the crystal lattice is independent of driving strength and detuning. We apply a polaron master equation to capture the non-Markovian dynamics of the ground state vibrational manifolds. These results provide insight into the fundamental limitations for photon coherence from solid-state quantum emitters, with the consequence that deterministic single-shot quantum protocols are impossible and inherently probabilistic approaches must be embraced.Comment: 16 pages [with supplementary information], 8 figure

Electron Removal Self Energy and its application to Ca2CuO2Cl2

We propose using the self energy defined for the electron removal Green's function. Starting from the electron removal Green's function, we obtained expressions for the removal self energy Sigma^ER (k,omega) that are applicable for non-quasiparticle photoemission spectral functions from a single band system. Our method does not assume momentum independence and produces the self energy in the full k-omega space. The method is applied to the angle resolved photoemission from Ca_2CuO_2Cl_2 and the result is found to be compatible with the self energy value from the peak width of sharp features. The self energy is found to be only weakly k-dependent. In addition, the Im Sigma shows a maximum at around 1 eV where the high energy kink is located.Comment: 5 pages, 3 figure

Prevalence and genetic diversity of Blastocystis in family units living in the United States

The human gut is host to a diversity of microorganisms including the single-celled microbial eukaryote Blastocystis. Although Blastocystis has a global distribution, there is dearth of information relating to its prevalence and diversity in many human populations. The mode of Blastocystis transmission to humans is also insufficiently characterised, however, it is speculated to vary between different populations. Here we investigated the incidence and genetic diversity of Blastocystis in a US population and also the possibility of Blastocystis human-human transmission between healthy individuals using family units (N = 50) living in Boulder, Colorado as our sample-set. Ten of the 139 (~ 7%) individuals in our dataset were positive for Blastocystis, nine of whom were adults and one individual belonging to the children/adolescents group. All positive cases were present in different family units. A number of different Blastocystis subtypes (species) were detected with no evidence of mixed infections. The prevalence of Blastocystis in this subset of the US population is comparatively low relative to other industrialised populations investigated to date; however, subtype diversity was largely consistent with that previously reported in studies of European populations. The distribution of Blastocystis within family units indicates that human-human transmission is unlikely to have occurred within families that participated in this study. It is not unexpected that given the world-wide variation in human living conditions and lifestyles between different populations, both the prevalence of Blastocystis and its mode of transmission to humans may vary considerably

Perfect State Transfer in PT-symmetric Non-Hermitian Networks

We systematically study the parity- and time-reversal (PT) symmetric non-Hermitian version of a quantum network proposed in the paper of Christandl et al. [Phys. Rev. Lett. 92, 187902 (2004)]. The nature of this model shows that it is a paradigm to demonstrate the complex relationship between the pseudo-Hermitian Hamiltonian and its Hermitian counterpart as well as a candidate in the experimental realization to simulate PT-symmetry breaking. We also show that this model allows a conditional perfect state transfer within the unbroken PT-symmetry region but not an arbitrary one. This is due to the fact that the evolution operator at a certain period is equivalent to the PT operator for the real-valued wave function in the elaborate PT-symmetric Hilbert space.Comment: 7 pages, 3 figure

Recovery of the orbital parameters and pulse evolution of V0332+53 during a huge outburst

The high mass X-ray binary (HMXB) V0332+53 became active at the end of 2004 and the outburst was observed at hard X-rays by RXTE and INTEGRAL. Based on these hard X-ray observations, the orbital parameters are measured through fitting the Doppler-shifted spin periods. The derived orbital period and eccentricity are consistent with those of Stella et al. (1985) obtained from EXOSAT observations, whereas the projected semimajor axis and the periastron longitude are found to have changed from 48$\pm$4 to 86$^{+6}_{-10}$ lt-s and from 313$^{\circ}$$\pm$10 to 283$^{\circ}$$\pm$14, respectively. This would indicate an angular speed of $\geq$ 1.5$^{\circ}$$\pm$0.8 yr$^{-1}$ for rotation of the orbit over the past 21 years. The periastron passage time of MJD 53367$\pm$1 is just around the time when the intensity reached maximum and an orbital period earlier is the time when the outburst started. This correlation resembles the behavior of a Type I outburst. During outburst the source spun up with a rate of 8.01$^{+1.00}_{-1.14}$$\times10^{-6}$ s day$^{-1}$. The evolution of pulse profile is highly intensity dependent. The separation of double pulses remained almost constant ($\sim$ 0.47) when the source was bright, and dropped to 0.37 within $\leq$ 3 days as the source became weaker. The pulse evolution of V0332+53 may correlate to the change in dominance of the emission between fan-beam and pencil-beam mechanisms.Comment: 13 pages, 3 figures, accepted for publication in ApJ

Effect of an Improved Molecular Potential on Strong-Field Tunneling Ionization of Molecules

We study the effect of one-electron model potentials on the tunneling ionization rates of molecules in strong fields. By including electron correlation using the modified Leeuwen-Baerends (LB α) model, the binding energies of outer shells of molecules are significantly improved. However, we show that the tunneling ionization rates from the LB α do not differ much from the earlier calculations [Phys. Rev. A 81, 033423 (2010)], in which the local correlation potential was neglected

Shock wave boundary layer interaction controlled by surface arc plasma actuators

An array of 16 surface arc plasma actuators (SAPAs) is employed to control the shock wave boundary layer interaction (SWBLI) at a 26° compression ramp in a Mach 2.0 flow. A new electrical circuit is used to actuate all 16 SAPAs. The electrical measurement reveals significant augmentation in peak current (200 A) and an energy deposition of 1.05 J, which are the nominal characteristics of the setup. The SAPA array is later applied for SWBLI control. The actuator array is placed upstream of the SWBLI and operates at four different frequencies, namely, 500 Hz, 1 kHz, 2 kHz, and 5 kHz. In the wind tunnel experiment, high-speed schlieren at 25 000 frames per second is used for flow visualization. The shock wave system is modified significantly by the controlling gas blobs (CGBs) or controlling gas bulbs (CGBUs) generated by SAPAs. The foot portion of the separation shock wave disappears, and the oblique shock wave bifurcates when the CGBs pass through the interaction region. The shock weakening effect is further verified through the rms of the schlieren intensity of the same phase