Related papers: A conditional-phase switch at the single-photon le…
We propose a method to induce strong effective interactions between photons mediated by an atomic ensemble. To achieve this, we use the so-called stationary light effect to enhance the interaction. Regardless of the single-atom coupling to…
Detailed investigations of single photon 1st-order interferences of separated emitters allow for analyzing the role of the mode function in quantum optics. In an earlier Young's double slit experiment using a higher spatial light mode some…
We describe a scheme for producing conditional nonlinear phase shifts on two-photon optical fields using an interaction with one or more ancilla two-level atomic systems. The conditional field state transformations are induced by using high…
Engineering deterministic photonic gates with simple resources is one of the long-standing challenges in photonic quantum computing. Here, we design a passive conditional gate between co-propagating photons using an array of only two-level…
Two photons in free space pass each other undisturbed. This is ideal for the faithful transmission of information, but prohibits an interaction between the photons as required for a plethora of applications in optical quantum information…
We show that the simultaneous interaction of two single-photon fields with a single atom in the V configuration can in principle produce a conditional phase gate of arbitrarily high fidelity, for an appropriate choice of the interaction…
We show that an array of identical two level systems coupled losslessly to a one dimensional waveguide is able to realize a high fidelity conditional phase shift useful for quantum logic. We propose two arrangements of emitters (one that…
We theoretically investigate the implementation of a quantum phase gate in a system constituted by a single atom inside an optical cavity, based on the electromagnetically induced transparency effect. Firstly we show that a probe pulse can…
We analyze in detail the proposal for a two-qubit gate for travelling single-photon qubits recently presented by C. Ottaviani \emph{et al}. [Phys. Rev. A \textbf{73}, 010301(R) (2006)]. The scheme is based on an ensemble of five-level atoms…
In analogy to transistors in classical electronic circuits, a quantum optical switch is an important element of quantum circuits and quantum networks. Operated at the fundamental limit where a single quantum of light or matter controls…
Entangled photon pairs are crucial resources for quantum information processing protocols. Via the process of spontaneous parametric down-conversion (SPDC), we can generate these photon pairs using bulk nonlinear crystals. Traditionally,…
We present a full quantum treatment of a five-level atomic system coupled to two quantum and two classical light fields. The two quantum fields undergo a cross-phase modulation induced by electro-magnetically induced transparency. The…
Realizing a sensitive photon-number-dependent phase shift on a light beam is required both in classical and quantum photonics. It may lead to new applications for classical and quantum photonics machine learning or pave the way for…
A deterministic photon-photon quantum-logic gate is a long-standing goal. Building such a gate becomes possible if a light pulse containing only one photon imprints a phase shift of $\pi$ onto another light field. Here we experimentally…
In spontaneous parametric down conversion (SPDC) based quantum information processing (QIP) experiments, there is a tradeoff between the coincide count rates (i.e. the pumping power of the SPDC), which limits the rate of the protocol, and…
It has been suggested that second-order nonlinearities could be used for quantum logic at the single-photon level. Specifically, successive two-photon processes in principle could accomplish the phase shift (conditioned on the presence of…
While the phase of a coherent light field can be precisely known, the phase of the individual photons that create this field, considered individually, cannot. Phase changes within single-photon wave packets, however, have observable…
Photon modes have an important role in characterizing the quantum sources of light. Proper coupling of various photon modes obtained in spontaneous parametric down conversion (SPDC) process in optical fibers is essential to generate an…
Deterministic quantum interactions between single photons and single quantum emitters are a vital building block towards the distribution of quantum information between remote systems. Deterministic photon-atom state transfer has been…
We propose a scheme for a deterministic controlled-phase gate between two photons based on the strong interaction between two stationary collective Rydberg excitations in an atomic ensemble. The distance-dependent character of the…