Photon antibunching in the fluorescence of a single dye molecule embedded in a thin polymer film

We used scanning confocal microscopy to study the fluorescence from a single terrylene molecule embedded in a thin polymer film of polymethyl methacrylate, at room temperature, with a high signal-to-background ratio. The photon-pair correlation function g((2))(tau) exhibits perfect photon antibunching at tau = 0 and a limit of 1.3, compatible with bunching associated with the molecular triplet state. Application of this molecular system to a triggered single-photon source based on single-molecule fluorescence is investigated.     

Photon antibunching in the fluorescence of individual color centers in diamond

We observed photon antibunching in the fluorescent light emitted from a single nitrogen-vacancy center in diamond at room temperature. The possibility of generating triggerable single photons with such a solid-state system is discussed.     

Photon antibunching in resonance fluorescence from impurity atoms in solids

The experimental conditions under which the intensity correlation function of resonance fluorescence of a single atom in a gas may be observed are briefly discussed. In general they can complicate the direct observation of photon antibunching. A direct observation should be possible in the case of a single impurity atom in a solid state matrix. The corresponding intensity correlation function is given.     

Photon antibunching in the photoluminescence spectra of a single carbon nanotube

We report the first observation of photon antibunching in the photoluminescence from single carbon nanotubes. The emergence of a fast luminescence decay component under strong optical excitation indicates that Auger processes are partially responsible for inhibiting two-photon generation. Additionally, the presence of exciton localization at low temperatures ensures that nanotubes emit photons predominantly one by one. The fact that multiphoton emission probability can be smaller than 5% suggests that carbon nanotubes could be used as a source of single photons for applications in quantum cryptography.     

Photon antibunching from a single quantum-dot-microcavity system in the strong coupling regime

We observe antibunching in the photons emitted from a strongly coupled single quantum dot and pillar microcavity in resonance. When the quantum dot was spectrally detuned from the cavity mode, the cavity emission remained antibunched, and also anticorrelated from the quantum dot emission. Resonant pumping of the selected quantum dot via an excited state enabled these observations by eliminating the background emitters that are usually coupled to the cavity. This device demonstrates an on-demand single-photon source operating in the strong coupling regime, with a Purcell factor of 61+/-7 and quantum efficiency of 97%.     

Photon bunching and antibunching in second harmonics generation

A nonperturbative, numerical study of photon statistics in second harmonics generation is presented.     

Photon distribution function in blinking fluorescence of individual molecules

A photon distribution function w_N(T) for blinking fluorescence with bright on- and dark off-intervals is derived. The function w_N(T) is expressed via few Poissonian functions each of which relates to corresponding exponential process in quantum dynamics of a given individual molecule. The distribution of photons is calculated for short, middle and long time intervals as compared to off-intervals. The distributions are much broader than Poissonian distribution and have rather complicated shape. If time resolution of an experiment does not permit us to see off-interval and, therefore, fluorescence looks like CW emission, the distribution of photons gives a signal about existence of hidden off- intervals in such CW fluorescence.     

Bunching and antibunching in the fluorescence of semiconductor nanocrystals

The fluorescence of single-colloidal CdSe quantum dots is investigated at room temperature by means of the autocorrelation function over a time scale of almost 12 orders of magnitude. Over a short time scale, the autocorrelation function shows complete antibunching, indicating single-photon emission and atomiclike behavior. Over longer time scales (up to tens of seconds), we measure a bunching effect that is due to fluorescence intermittency and that cannot be described by fluctuations between two states with constant rates. The autocorrelation function also exhibits nonstationary behavior related to power-law distributions of On and Off times.     

Photon statistics in single molecule fluorescence with Rabi oscillations

An expression for the distribution function of photons detected in non-resonant single molecule fluorescence excited by CW-laser light is derived. Numerical calculations of the photon distribution for fluorescence whose autocorrelation function exhibits Rabi oscillations are carried out. It is found that phase memory does not influence noticeably on the photon distribution function in non-resonant fluorescence.     

q-奇相干场与级联型三能级原子相互作用中场的反聚束效应

提出了q-奇相干场与级联型三能级原子相互作用的非线性理论,求得了在相互作用绘景中薛定谔方程的形式解及其在其态下的期望值。利用数值计算讨论了q形变对相互作用中场的反聚束效应的影响。经研究发现,q形变对反聚束效应的调制能力很强,反映出了q形变的非线性行为对量子相干性的干扰以及对量子特性的影响。当q→1时,恢复为普通的线性理论。     

Photon,quantum and collective,effects from rydberg atoms in cavities

I review some theories of the interaction ofN Rydberg atoms interacting collectively with radiation in microwave cavities. The radiation may be incoherent (black body) radiation or it may be coherent. In the former case theories of the steady state inversion and of the superradiance from initially inverted atoms in low-Q cavities agree well with experimental observations. In the latter case in low-Q cavities ‘phase transitions’ of both first and second order types are predicted and should be observable by monitoring the output of an atomic beam by an atomic ionisation detector. The first order transition which occurs at opposite detunings of the cavity and atoms from the frequency of the coherent driving field is of “optically” bistable type but hysteresis is suppressed by quantum fluctuations which can be large in the cavity field close to the transition. I also review a theory of the spectra from single atoms in cavities ofarbitrary Q containing a few microwave photons. A transition from a single peaked Lorentzian spectrum at low-Q to a double-peaked spectrum forQ≃10⁶ is predicted and peaks representing one or more photon transitions of the Jaynes-Cummings model are also expected to be observable at these or largerQ values. The collective theories are all based onN atom Dicke type models driven by the coherent or incoherent field. Substantial squeezing of the fluorescent radiation field from these Dicke models is also predicted and may be observable with Rydberg atoms.     

Photon antibunching in the spontaneous emission from dicke's superradiant state

Quantum statistical properties of the spontaneous emission from a system of N identical two-level atoms in Dicke's superradiant state initially are studied analytically by solving exactly the superradiant master equation. It is found that photon antibunching exists in approximately the first half of the superradiant pulse duration.     

Efficiency of intramolecular electronic energy transfer in coumarin bichromophoric molecules

Intramolecular energy transfer in bichromorhoric molecules consisting of two coumarins linked by a variable number of methylene groups (n = 3, 4, 8, 12), was studied with special attention to the effects of n, temperature, viscosity and solvent nature on the efficiency of transfer. The validity of model compounds for the donor and acceptor moieties was carefully examined. Fluorescence polarization experiments revealed that a non-randomicity of mutual orientation of donor and acceptor can only be small, if any. Dual fluorescence from donor and acceptor was observed in propylene glycol whatever the value of n and at any temperature ranging from -60 to 60°C. Fluorescence from the donor was not detectable in dimethylformamide owing to the very low quantum yield of the donor in this solvent. Transfer efficiencies were determined by three steady-state methods and were found to be more dependent on n in dimethylformamide than in propylene glycol. Incomplete energy transfer is clearly shown in the case of dimethylformamide as a solvent. The effects of temperature are weak in the -60, + 60°C range. The results are discussed in light of theories of energy transfer.     

Photon statistics in collective double optical resonant process

The photon statistics of spectrum components of scattered light in a collective double optical resonant process is discussed. The correlation and anticorrelation between spectrum components are observed.