By harnessing aspects of quantum mechanics, communication and information processing could be radically transformed. Promising forms technology include optical cryptographic systems computing using photons for logic operations. As with current systems, some form memory will required. Quantum repeaters, which are required long distance key distribution, require as do deterministic gates computing. In this paper we present results from a coherent based on warm rubidium vapour show 87%...

Optical photons are powerful carriers of quantum information, which can be delivered in free space by satellites or fibers on the ground over long distances. Entanglement states distances empower computing, communications, and sensing. Quantum optical memories devices designed to store information form stationary excitations, such as atomic coherence, capable coherently mapping these excitations flying qubits. effectively manipulate states, making them indispensable elements future...

We propose a photon echo quantum memory scheme using detuned Raman coupling to long-lived ground states. In contrast previous three-level schemes based on controlled reversible inhomogeneous broadening that use sequences of pi pulses, the does not require accurate control dynamics present proof-of-principle experimental realization our proposal rubidium atoms in warm vapor cell. The resonance line is broadened magnetic field varies linearly along direction light propagation. Inverting...

Deterministic optical quantum logic requires a nonlinear process that alters the phase of state by $\pi$ through interaction with only one photon. Here, we demonstrate large conditional cross-phase modulation between signal field, stored inside an atomic memory, and control photon traverses high-finesse cavity containing memory. This approach avoids fundamental limitations associated multimode effects for traveling photons. We measure shift up to $\pi/3$ retrieved photons, confirm...

Natural graphite was oxidized via the Hummer's method and sonicated to obtain graphene oxide (GO). A three-step modification process performed attach a reversible addition–fragmentation chain transfer (RAFT)-agent onto GO surface GO-RAFT nanosheets. RAFT polymerization of 2-hydroxyethyl methacrylate (HEMA) acrylic acid (AA) by using azobisisobutyronitrile (AIBN) as initiator. After separation free chains, GO-P(HEMA) GO-P(HEMA-co-AA) were obtained. Fourier transform infrared (FTIR),...

Three-level atomic gradient echo memory (lambda-GEM) is a proposed candidate for efficient quantum storage and linear optical computation with time-bin multiplexing. In this paper we investigate the spatial multimode properties of lambda-GEM system. Using high-speed triggered CCD, demonstrate complex modes images. We also present an in-principle demonstration multiplexing by showing selective recall elements stored spin wave. our measurements, consider effect diffusion within vapour its role...

Large nonlinearity at the single-photon level can pave way for implementation of universal quantum gates. However, realizing large and noiseless such low light levels has been a great challenge scientists in past decade. Here, we propose scheme that enables substantial nonlinear interaction between two fields are both stored an atomic memory. Semiclassical simulations demonstrate feasibility achieving cross-phase modulation (XPM) down to level. The proposed be used implement parity gates...

A seven-step approach was developed to synthesize poly(acrylic acid-b-2-hydroxyethyl methacrylate) [P(AA-b-HEMA)]-based temperature- and pH-sensitive hollow nanospheres. Silica nanoparticles were used as primary cores that could be etched with an aqueous hydrofluoric acid (HF) solution. surface-attached atom transfer radical polymerization initiator converted a reversible addition–fragmentation chain (RAFT) agent, AA HEMA polymerized via "grafting from" RAFT polymerization. The PAA block...

The micro-Wilhelmy method is a well-established of determining surface tension by measuring the force withdrawing tens microns to millimeters in diameter cylindrical wire or fiber from liquid. A comparison insertion retraction can also be used determine contact angle with fiber. Given limited availability atomic microscope (AFM) probes that have long constant tips, force−distance (F−D) curves using standard tapered tips been difficult relate tension. In this report, metal alloy nanowires...

A specific structure of doped graphene with substituted silicon impurity is introduced and ab initio density-functional approach applied for the energy band calculation proposed structure. Using different sites in host graphene, effect concentration unit cell geometry on bandgap also investigated. Chemically, silicon-doped results an gap as large 2 eV according to theory calculations. As authors will show, contrast previous engineering methods, such has significant advantages including wide...

We demonstrate the feasibility of levitating a small mirror using only radiation pressure. In our scheme, is supported by tripod where each leg Fabry-Perot cavity. The macroscopic state coherently coupled to supporting cavity modes allowing coherent interrogation and manipulation motion. proposed scheme an extreme example optical spring, mechanical oscillator isolated from environment its frequency can be manipulated solely through fields. model stability system find three-dimensional...

Quantum memories are an integral component of quantum repeaters—devices that will allow the extension key distribution to communication ranges beyond permissible by passive transmission. A memory for this application needs be highly efficient and have coherence times approaching a millisecond. Here we report on work towards goal, with development 87Rb magneto-optical trap peak optical depth 1000 D2 F = 2 → F' 3 transition using spatial temporal dark spots. With purpose-built cold atomic...