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Dive into the research topics where Andrew D. Greentree is active.

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Featured researches published by Andrew D. Greentree.


Nature Physics | 2006

Room-temperature coherent coupling of single spins in diamond

Torsten Gaebel; M Domhan; I. Popa; Christoffer Wittmann; Philipp Neumann; Fedor Jelezko; James R. Rabeau; N. Stavrias; Andrew D. Greentree; Steven Prawer; Jan Meijer; Jason Twamley; P. R. Hemmer; Jörg Wrachtrup

Coherent coupling between single quantum objects is at the very heart of modern quantum physics. When the coupling is strong enough to prevail over decoherence, it can be used to engineer quantum entangled states. Entangled states have attracted widespread attention because of applications to quantum computing and long-distance quantum communication. For such applications, solid-state hosts are preferred for scalability reasons, and spins are the preferred quantum system in solids because they offer long coherence times. Here we show that a single pair of strongly coupled spins in diamond, associated with a nitrogen-vacancy defect and a nitrogen atom, respectively, can be optically initialized and read out at room temperature. To effect this strong coupling, close proximity of the two spins is required, but large distances from other spins are needed to avoid deleterious decoherence. These requirements were reconciled by implanting molecular nitrogen into high-purity diamond.


Reports on Progress in Physics | 2011

Diamond-based single-photon emitters

Igor Aharonovich; Stefania Castelletto; David A. Simpson; Chun-Hsu Su; Andrew D. Greentree; Steven Prawer

The exploitation of emerging quantum technologies requires efficient fabrication of key building blocks. Sources of single photons are extremely important across many applications as they can serve as vectors for quantum information—thereby allowing long-range (perhaps even global-scale) quantum states to be made and manipulated for tasks such as quantum communication or distributed quantum computation. At the single-emitter level, quantum sources also afford new possibilities in terms of nanoscopy and bio-marking. Color centers in diamond are prominent candidates to generate and manipulate quantum states of light, as they are a photostable solid-state source of single photons at room temperature. In this review, we discuss the state of the art of diamond-based single-photon emitters and highlight their fabrication methodologies. We present the experimental techniques used to characterize the quantum emitters and discuss their photophysical properties. We outline a number of applications including quantum key distribution, bio-marking and sub-diffraction imaging, where diamond-based single emitters are playing a crucial role. We conclude with a discussion of the main challenges and perspectives for employing diamond emitters in quantum information processing.


Physical Review Letters | 2006

Coherent population trapping of single spins in diamond under optical excitation

Charles Santori; Philippe Tamarat; Philipp Neumann; Jörg Wrachtrup; David A. Fattal; Raymond G. Beausoleil; James R. Rabeau; P. Olivero; Andrew D. Greentree; Steven Prawer; Fedor Jelezko; P. R. Hemmer

Coherent population trapping is demonstrated in single nitrogen-vacancy centers in diamond under optical excitation. For sufficient excitation power, the fluorescence intensity drops almost to the background level when the laser modulation frequency matches the 2.88 GHz splitting of the ground states. The results are well described theoretically by a four-level model, allowing the relative transition strengths to be determined for individual centers. The results show that all-optical control of single spins is possible in diamond.


Physical Review Letters | 2006

Stark Shift Control of Single Optical Centers in Diamond

Philippe Tamarat; Torsten Gaebel; Rabeau; Mughees Khan; Andrew D. Greentree; H Wilson; Lcl Hollenberg; Steven Prawer; P. R. Hemmer; Fedor Jelezko; Jörg Wrachtrup

Lifetime-limited optical excitation lines of single nitrogen-vacancy (NV) defect centers in diamond have been observed at liquid helium temperature. They display unprecedented spectral stability over many seconds and excitation cycles. Spectral tuning of the spin-selective optical resonances was performed via the application of an external electric field (i.e., the Stark shift). A rich variety of Stark shifts were observed including linear as well as quadratic components. The ability to tune the excitation lines of single NV centers has potential applications in quantum information processing.


Physical Review B | 2006

Two-dimensional architectures for donor-based quantum computing

Lloyd C. L. Hollenberg; Andrew D. Greentree; Austin G. Fowler; Cameron J. Wellard

Through the introduction of a new electron spin transport mechanism, a 2D donor electron spin quantum computer architecture is proposed. This design addresses major technical issues in the original Kane design, including spatial oscillations in the exchange coupling strength and cross-talk in gate control. It is also expected that the introduction of nonlocality in qubit interaction will significantly improve the scaling fault-tolerant threshold over the nearest-neighbor linear array.


Physical Review B | 2004

Coherent electronic transfer in quantum dot systems using adiabatic passage

Andrew D. Greentree; Jared H. Cole; A. R. Hamilton; Lloyd C. L. Hollenberg

We describe a scheme for using an all-electrical, rapid, adiabatic population transfer between two spatially separated dots in a triple-quantum dot system. The electron spends no time in the middle dot and does not change its energy during the transfer process. Although a coherent population transfer method, this scheme may well prove useful in incoherent electronic computation (for example quantum-dot cellular automata) where it may provide a coherent advantage to an otherwise incoherent device. It can also be thought of as a limiting case of type II quantum computing, where sufficient coherence exists for a single gate operation, but not for the preservation of superpositions after the operation. We extend our analysis to the case of many intervening dots and address the issue of transporting quantum information through a multi-dot system.


Advanced Materials | 2008

Fabrication of Ultrathin Single-Crystal Diamond Membranes†

Barbara A. Fairchild; P. Olivero; Sergey Rubanov; Andrew D. Greentree; F. C. Waldermann; Robert A. Taylor; Ian A. Walmsley; Jason M. Smith; Shane Huntington; Brant C. Gibson; D.N. Jamieson; Steven Prawer

A method for preparing ultrathin single-crystal diamond membranes suitable for post-processing and liftout, is reported. The proposed method used single-crystal diamond substrates and two-energy ion implant process for the fabrication of thin diamond membranes. Two ion-implant process was used in this method to prepare two different damage layers within diamond sample. This method can be used for preparing integrated quantum-photonic structure based on color center in diamond. This method can also be used for fabricating various structures including Bragg gratings and whispering gallery mode resonators. A significant application of the diamond nanostructures is to fabricate the micro- and nanoscale cantilevers. It was also observed that the fabricated single-crystal diamond are suitable for another FIB processing.


Nano Letters | 2009

Two-level ultrabright single photon emission from diamond nanocrystals

Igor Aharonovich; Stefania Castelletto; David A. Simpson; Alastair Stacey; J. C. McCallum; Andrew D. Greentree; Steven Prawer

The fabrication of stable ultrabright single photon sources operating at room temperature is reported. The emitter is based on a color center within a diamond nanocrystal grown on a sapphire substrate by chemical vapor deposition method and exhibits a two-level electronic behavior with a maximum measured count rate of 3.2 x 10(6) counts/s at saturation. The emission is centered at approximately 756 nm with a full width at half-maximum approximately 11 nm and an excited state lifetime of 3.7 ns. These unique properties make it a leading candidate for quantum photonics and communication applications as well as for cellular biomarking.


Materials Today | 2008

Diamond integrated quantum photonics

Andrew D. Greentree; Barbara A. Fairchild; Faruque M. Hossain; Steven Prawer

Diamond is a leading contender as the material of choice for the quantum computer industry. This potential arises mainly from the quantum properties of color centers in diamond. However, before diamond can realize its full potential, the technology to fabricate and sculpt diamond as well as, if not better than, silicon must be developed. A comprehensive processing capability for diamond that will allow the fabrication of qubits and their associated photonic structures is required. Here we describe the remarkable properties of diamond color centers, and the techniques being developed to engineer qubits and sculpt monolithic structures around them. Finally we outline some of the new proposals that use engineered diamond to realize tasks not possible with existing technologies.


Physical Review B | 2010

Chromium single-photon emitters in diamond fabricated by ion implantation

Igor Aharonovich; Stefania Castelletto; B. C. Johnson; J. C. McCallum; David A. Simpson; Andrew D. Greentree; Steven Prawer

Controlled fabrication and identification of bright single-photon emitters is at the heart of quantum optics. Here we demonstrate controlled engineering of a chromium bright single-photon source in bulk diamond by ion implantation. The Cr center has fully polarized emission with a zero-phonon line centered at 749 nm, full width at half maximum of 4 nm, an extremely short lifetime of ?1ns, and a count rate of 0.5× 106 counts/s. By combining the polarization measurements and the vibronic spectra, a model of the center has been proposed consisting of one interstitial chromium atom with a transition dipole along one of the (100) directions

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Chun-Hsu Su

University of Melbourne

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J. O. Orwa

University of Melbourne

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