Coherent preparation by laser light of quantum states of atoms and molecules can lead to quantum interference in the amplitudes of optical transitions. In this way the optical properties of a medium can be dramatically modified, leading to electromagnetically induced transparency and related effects, which have placed gas-phase systems at the center of recent advances in the development of media with radically new optical properties. This article reviews these advances and the new possibilities they offer for nonlinear optics and quantum information science. As a basis for the theory of electromagnetically induced transparency the authors consider the atomic dynamics and the optical response of the medium to a continuous-wave laser. They then discuss pulse propagation and the adiabatic evolution of field-coupled states and show how coherently prepared media can be used to improve frequency conversion in nonlinear optical mixing experiments. The extension of these concepts to very weak optical fields in the few-photon limit is then examined. The review concludes with a discussion of future prospects and potential new applications.

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Electromagnetically induced transparency : Optics in coherent media

日本物理学会誌及びJournal of the Physical Society of Japanの月刊について

The nitrogen-vacancy (NV) colour centre in diamond is an important physical system for emergent quantum technologies, including quantum metrology, information processing and communications, as well as for various nanotechnologies, such as biological and sub-diffraction limit imaging, and for tests of entanglement in quantum mechanics. Given this array of existing and potential applications and the almost 50 years of NV research, one would expect that the physics of the centre is well understood, however, the study of the NV centre has proved challenging, with many early assertions now believed false and many remaining issues yet to be resolved. This review represents the first time that the key empirical and ab initio results have been extracted from the extensive NV literature and assembled into one consistent picture of the current understanding of the centre. As a result, the key unresolved issues concerning the NV centre are identified and the possible avenues for their resolution are examined.

The nitrogen-vacancy colour centre in diamond

A nanoscale thermometry technique that uses coherent manipulation of the electronic spin associated with nitrogen–vacancy colour centres in diamond makes it possible to detect temperature variations as small as 1.8 millikelvin in ultrapure samples and to control and map temperature gradients within living cells. A nanoscale thermometer capable of subdegree temperature resolution and of integration within living cells could provide a powerful new tool for many areas of biological and medical research. This paper describes a new probe for nanoscale thermometry that achieves just that. The device uses quantum manipulation of nitrogen–vacancy colour centres in diamond nanocrystals. These harbour single electron spins and have specific fluorescence properties that are sensitively dependent on the local temperature. The authors show that they can be accurately measured with a spatial resolution down to 200 nm. By introducing both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, they demonstrate temperature-gradient control and mapping at the subcellular level. Sensitive probing of temperature variations on nanometre scales is an outstanding challenge in many areas of modern science and technology1. In particular, a thermometer capable of subdegree temperature resolution over a large range of temperatures as well as integration within a living system could provide a powerful new tool in many areas of biological, physical and chemical research. Possibilities range from the temperature-induced control of gene expression2,3,4,5 and tumour metabolism6 to the cell-selective treatment of disease7,8 and the study of heat dissipation in integrated circuits1. By combining local light-induced heat sources with sensitive nanoscale thermometry, it may also be possible to engineer biological processes at the subcellular level2,3,4,5. Here we demonstrate a new approach to nanoscale thermometry that uses coherent manipulation of the electronic spin associated with nitrogen–vacancy colour centres in diamond. Our technique makes it possible to detect temperature variations as small as 1.8 mK (a sensitivity of 9 mK Hz−1/2) in an ultrapure bulk diamond sample. Using nitrogen–vacancy centres in diamond nanocrystals (nanodiamonds), we directly measure the local thermal environment on length scales as short as 200 nanometres. Finally, by introducing both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, we demonstrate temperature-gradient control and mapping at the subcellular level, enabling unique potential applications in life sciences.

/pdf/nanometre-scale-thermometry-in-a-living-cell-2rnqt7l5id.pdf

Nanometre-scale thermometry in a living cell

Efficient interfaces between photons and quantum emitters form the basis for quantum networks and enable optical nonlinearities at the single-photon level. We demonstrate an integrated platform for scalable quantum nanophotonics based on silicon-vacancy (SiV) color centers coupled to diamond nanodevices. By placing SiV centers inside diamond photonic crystal cavities, we realize a quantum-optical switch controlled by a single color center. We control the switch using SiV metastable states and observe optical switching at the single-photon level. Raman transitions are used to realize a single-photon source with a tunable frequency and bandwidth in a diamond waveguide. By measuring intensity correlations of indistinguishable Raman photons emitted into a single waveguide, we observe a quantum interference effect resulting from the superradiant emission of two entangled SiV centers.

https://science.sciencemag.org/content/sci/354/6314/847.full.pdf

An integrated diamond nanophotonics platform for quantum optical networks

The negatively charged silicon-vacancy (${\mathrm{SiV}}^{\ensuremath{-}}$) color center in diamond has recently emerged as a promising system for quantum photonics. Its symmetry-protected optical transitions enable the creation of indistinguishable emitter arrays and deterministic coupling to nanophotonic devices. Despite this, the longest coherence time associated with its electronic spin achieved to date ($\ensuremath{\sim}250\text{ }\text{ }\mathrm{ns}$) has been limited by coupling to acoustic phonons. We demonstrate coherent control and suppression of phonon-induced dephasing of the ${\mathrm{SiV}}^{\ensuremath{-}}$ electronic spin coherence by 5 orders of magnitude by operating at temperatures below 500 mK. By aligning the magnetic field along the ${\mathrm{SiV}}^{\ensuremath{-}}$ symmetry axis, we demonstrate spin-conserving optical transitions and single-shot readout of the ${\mathrm{SiV}}^{\ensuremath{-}}$ spin with 89% fidelity. Coherent control of the ${\mathrm{SiV}}^{\ensuremath{-}}$ spin with microwave fields is used to demonstrate a spin coherence time ${T}_{2}$ of 13 ms and a spin relaxation time ${T}_{1}$ exceeding 1 s at 100 mK. These results establish the ${\mathrm{SiV}}^{\ensuremath{-}}$ as a promising solid-state candidate for the realization of quantum networks.

Silicon-Vacancy Spin Qubit in Diamond: A Quantum Memory Exceeding 10 ms with Single-Shot State Readout.

When a resonance associated with electromagnetically induced transparency in an atomic ensemble is modulated by an off-resonant standing light wave, a band of frequencies can appear for which light propagation is forbidden. We show that dynamic control of such a band gap can be used to coherently convert a propagating light pulse into a stationary excitation with nonvanishing photonic component. This can be accomplished with high efficiency and negligible noise even at the level of few-photon quantum fields thereby facilitating possible applications in quantum nonlinear optics and quantum information.

Manipulating Light Pulses via Dynamically Controlled Photonic Band gap

Metasurfaces mould the flow of classical light waves by engineering subwavelength patterns from dielectric or metallic thin films. We introduce and analyse a method in which quantum operator-valued reflectivity can be used to control both the spatiotemporal and quantum properties of transmitted and reflected light. Such quantum metasurfaces are realized by entangling the macroscopic response of atomically thin atom arrays to light. We show that such a system allows for parallel quantum operations between atoms and photons as well as for the generation of highly entangled photonic states such as photonic Greenberger–Horne–Zeilinger and three-dimensional cluster states suitable for quantum information processing. We analyse the influence of imperfections as well as specific implementations based on atom arrays excited into Rydberg states. A kind of quantum metasurface made of an atom array is proposed, providing the possibility to control both spatiotemporal and quantum properties of transmitted and reflected light.

Quantum metasurfaces with atom arrays

https://apps.dtic.mil/sti/pdfs/AD1046015.pdf

M. D. Lukin

Papers

An integrated diamond nanophotonics platform for quantum optical networks

Silicon-Vacancy Spin Qubit in Diamond: A Quantum Memory Exceeding 10 ms with Single-Shot State Readout.

Manipulating Light Pulses via Dynamically Controlled Photonic Band gap

Quantum metasurfaces with atom arrays

Collective Atomic Scattering and Motional Effects in a Dense Coherent Medium (Open Access Publisher's Version)