The ability of the internal states a working fluid to be in coherent superposition is one basic properties quantum heat engine. It was recently predicted that regime small engine action, this can enable produce more power than any equivalent classical also same regime, presence such coherence causes different types engines become thermodynamically equivalent. Here, we use an ensemble nitrogen vacancy centers diamond for implementing two engines, and experimentally observe both effects.

Quantum networks promise to revolutionise computing, simulation, and communication. Light is the ideal information carrier for quantum networks, as its properties are not degraded by noise in ambient conditions, it can support large bandwidths enabling fast operations a capacity. memories, devices that store, manipulate, release on demand light, have been identified critical components of photonic because they facilitate scalability. However, any introduced memory render device classical...

Broadband quantum memories hold great promise as multiplexing elements in future photonic information protocols. Alkali vapour Raman combine high-bandwidth storage, on-demand read-out, and operation at room temperature without collisional fluorescence noise. However, previous implementations have required large control pulse energies suffered from four-wave mixing Here we present a memory where the storage interaction is enhanced by low-finesse birefringent cavity tuned into simultaneous...

Broadband quantum memories, used as temporal multiplexers, are a key component in photonic information processing, they make repeat-until-success strategies scalable. We demonstrate prototype system, operating on-demand, by interfacing warm vapour, high time-bandwidth-product Raman memory with travelling wave spontaneous parametric down-conversion source. store single photons and observe clear influence of the input photon statistics on retrieved light, which we find currently to be limited...

Solid-state impurity spins with optical control are currently investigated for quantum networks and repeaters. Among these, rare-earth-ion doped crystals promising as memories light, potentially long storage time, high multimode capacity, bandwidth. However, there is often a tradeoff between bandwidth, which favors electronic spin, memory nuclear spins. Here, we present experiments using highly hybridized electron-nuclear hyperfine states in...

We show that cold Rydberg gases enable an efficient six-wave mixing process where terahertz or microwave fields are coherently converted into optical and vice versa. This is made possible by the long lifetime of states, strong coupling millimeter waves to transitions a quantum interference effect related electromagnetically induced transparency. Our frequency conversion scheme applies broad spectrum due abundance within manifold, we discuss two implementations based on focussed beams wave...

We present an experimental realization of a noise-free and high-bandwidth quantum memory scheme using rubidium vapor that is confined within the hollow core photonic crystal fiber. achieve same internal efficiencies as similar free-space experiments (30%) for 4.5-ns-long optical pulses but with 100-fold reduction in control-field power required. Modeling indicates this efficiency could be improved to 88% higher control powers implementation techniques such light-induced atomic desorption...

Alkali-filled hollow-core fibers are a promising medium for investigating light-matter interactions, especially at the single-photon level, due to tight confinement of light and high optical depths achievable by light-induced atomic desorption (LIAD). However, until now these large could only be generated seconds, most once per day, severely limiting practicality technology. Here we report generation highest observed transient (>10(5) up minute) persistent (>2000 hours) alkali vapors in...

Quantum memories, capable of storing single photons or other quantum states light, to be retrieved on-demand, offer a route large-scale information processing with light. A promising class memories is based on far-off-resonant Raman absorption in ensembles $\Lambda$-type atoms. However at room temperature these systems exhibit unwanted four-wave mixing, which prohibitive for applications the single-photon level. Here we show how this noise can suppressed by placing storage medium inside...

We demonstrate a double optical frequency reference (1529 and 1560 nm) for the telecom C-band using 87Rb modulation transfer spectroscopy. The two frequencies are defined by 5S(1/2)F=2→5P(3/2)F'=3 two-level 5S(1/2)F=2→5P(3/2)F'=3→4D(5/2)F''=4 ladder transitions. examine sensitivity of stabilization to probe power magnetic field fluctuations, calculate its shift due residual amplitude modulation, estimate gas collisions. short-term Allan deviation was estimated from error signal slope Our...

It is proposed that the ground-state manifold of neutral nitrogen-vacancy center in diamond could be used as a quantum two-level system solid-state-based implementation broadband noise-free optical memory. The proposal based on same-spin $\ensuremath{\Lambda}$-type three-level created between two $E$ orbital ground states and ${A}_{1}$ excited state center, cross-linear polarization selection rules obtained with application transverse electric field or uniaxial stress. Possible decay...

We introduce a filter using noise-free quantum buffer with large optical bandwidth that can both temporal-spectral modes as well interconvert them and change their frequency. theoretically show such buffers optimally out noise, producing identical single photons from many distinguishable noisy single-photon sources the minimum required reduction in brightness. then experimentally demonstrate warm atomic system is matched to dots. Based on these experiments, simulations our outperform all...

Quantum memories with long storage times are key elements in long-distance quantum networks. The atomic frequency comb (AFC) memory particular has shown great promise to fulfill this role, having demonstrated multimode capacity and spin-photon correlations. However, the have so-far been limited about one millisecond, realized a Eu${}^{3+}$ doped Y${}_2$SiO${}_5$ crystal at zero applied magnetic field. Motivated by studies showing increased spin coherence under field, we developed AFC...

Raman interactions in alkali vapours are used applications such as atomic clocks, optical signal processing, generation of squeezed light and quantum memories for temporal multiplexing. To achieve a strong interaction the ensemble needs both large depth high level spin-polarisation. We implement technique known quenching using molecular buffer gas which allows near-perfect spin-polarisation over caesium vapour at depths up to factor 4 higher than can be achieved without quenching. use this...

Preparation of an atomic ensemble in a particular Zeeman state is critical step many protocols for implementing quantum sensors and memories. These devices can also benefit from optical fiber integration. In this work we describe experimental results supported by theoretical model single-beam pumping 87Rb atoms within hollow-core photonic crystal fiber. The observed 50% population increase the pumped F = 2, mF 2 substate along with depopulation remaining substates enabled us to achieve...

We have developed a novel protocol for broadband, noise-free light-matter interactions using off-resonant two-photon absorption.We then used this quantum ladder (QLAD) to store and retrieve 1.5 GHz bandwidth heralded single photons.

We implement a low-noise, broadband quantum memory for light via off-resonant two-photon absorption in warm atomic vapour. store heralded single photons and verify that the retrieved fields are anti-bunched.

Temporal modes (TMs) of pulsed single-photon states have been identified as appealing basis for quantum information science. Recent work has seen progress towards TM-selective operations based on nonlinear optics. Here, we demonstrate the first time a linear device, namely Raman memory in warm atomic Caesium vapour. We achieve switching fidelities 86.5% when operating with ns-duration pulses. These results pave way new applications, where TM-selection, TM-reshaping, and network...

Deterministic quantum information processing will require hybrid systems like an interface between microwave and optical photons. We propose a scheme for efficient, multimode coherent microwave-optical conversion based on frequency mixing in Rydberg atoms.

Quantum memories enable the synchronisation of photonic operations. Raman are a promising platform, but susceptible to four-wave mixing noise. We present demonstration cavity-enhanced memory, showing suppression mixing.