Simulating the photon stream of a real thermal light source.

We present a computer algorithm capable of simulating the photon stream and the corresponding temporal photon statistics of thermal light sources. The algorithm implements realistic experimental conditions, incorporating the relevant parameters of the source as well as of the detection process. The code is verified by comparing the temporal photon autocorrelation function computed from the simulations to the one measured with a real thermal light source. In view of the renewed interest for intensity interferometry in astronomy and the life sciences, such simulations become increasingly relevant.

Directional Dicke Subradiance with Nonclassical and Classical Light Sources.

We investigate Dicke subradiance of N≥2 distant quantum sources in free space, i.e., the spatial emission patterns of spontaneously radiating noninteracting multilevel atoms or multiphoton sources, prepared in totally antisymmetric states. We find that the radiated intensity is marked by a full suppression of spontaneous emission in particular directions. In resemblance to the analogous, yet inverted, superradiant emission profiles of N distant two-level atoms prepared in symmetric Dicke states, we call the corresponding emission patterns directional Dicke subradiance. We further derive that higher-order intensity correlations of the light emitted by statistically independent thermal light sources display the same directional Dicke subradiant behavior and show that it stems from the same interference phenomenon as in the case of quantum sources. We finally present measurements of directional Dicke subradiance for N=2,…,5 distant thermal light sources corroborating the theoretical findings.

Superresolving Imaging of Arbitrary One-Dimensional Arrays of Thermal Light Sources Using Multiphoton Interference.

We propose to use multiphoton interferences of photons emitted from statistically independent thermal light sources in combination with linear optical detection techniques to reconstruct, i.e., image, arbitrary source geometries in one dimension with subclassical resolution. The scheme is an extension of earlier work [S. Oppel et al., Phys. Rev. Lett. 109, 233603 (2012)], where N regularly spaced sources in one dimension were imaged by use of the Nth-order intensity correlation function. Here, we generalize the scheme to reconstruct any number of independent thermal light sources at arbitrary separations in one dimension, exploiting intensity correlation functions of order m≥3. We present experimental results confirming the imaging protocol and provide a rigorous mathematical proof for the obtained subclassical resolution.

Catastrophic associations predict level of change in anxiety sensitivity in response to cognitive-behavioural treatment for panic.

The aim of the present study was to elucidate one of the factors that might be responsible for the maintenance of panic patients' harmful beliefs about anxiety. Specifically, it was hypothesized that harmful beliefs about anxiety, i.e. anxiety sensitivity, is maintained in panic patients by automatic activation of idiographic catastrophic cognitions. To test this prediction, panic patients participated in a one-session cognitive-behavioural treatment of 4-8h to reduce anxiety sensitivity. The strength of automatic catastrophic cognitions in response to idiographic anxiety symptoms, measured with a modified semantic priming task, as well as the strength of the consciously accessible catastrophic meaning of these symptoms were assessed before treatment. In accordance with the hypothesis, stronger automatic catastrophic cognitions predicted a smaller reduction of anxiety sensitivity independently of the strength of conscious catastrophic cognitions. Moreover, in a first exploration, the strength of catastrophic associations was also shown to have an incremental predictive value for change in anxiety sensitivity beyond that of a number of demographic, clinical, treatment and assessment variables. The theoretical and clinical implications are discussed.

Panic patients reveal idiographic associations between anxiety symptoms and catastrophes in a semantic priming task.

In the present study, a modified semantic priming paradigm was used to test whether panic patients more strongly associate catastrophes with anxiety symptoms than nonclinical subjects. Subjects named catastrophic target words (e.g. infarction) and target words neutral to anxiety themes (e.g. weekend) that followed auditive prime sentences immediately (i.e.0ms) or with a delay (i.e. 1500ms). Prime sentences described the perception of anxiety symptoms (e.g. You feel tense) or sensations neutral to anxiety (You feel relaxed). Consistent with an earlier study [Schniering C.A., & Rapee, R.M. (1997). A test of the cognitive model of panic: Primed lexical decision in panic disorder. Journal of Anxiety Disorders, 11, 557-571] the two groups did not differ if semantic priming effects were calculated in the usual way, i.e. by averaging across identical stimuli for all subjects. As expected, however, panic patients demonstrated stronger semantic priming effects for catastrophes immediately following prime sentences if priming effects were calculated for idiographically selected stimuli. The latter result indicated stronger automatic associations between idiographic anxiety symptoms and catastrophes in panic patients consistent with the cognitive model of panic disorder (Clark, D.M. (1986). A cognitive approach to panic. Behaviour Research and Therapy, 24, 461-470). The restriction of stronger associations in panic patients to idiographic stimuli is explained from an evolutionary perspective.