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Journal Article•

Single spin detection by magnetic resonance force microscopy

Daniel Rugar
25 Mar 2005-Bulletin of the American Physical Society (American Physical Society)-
TL;DR: In this article, the authors reported the detection of an individual electron spin by magnetic resonance force microscopy (MRFM) and achieved a spatial resolution of 25nm in one dimension for an unpaired spin in silicon dioxide.
Abstract: Magnetic resonance imaging (MRI) is well known as a powerful technique for visualizing subsurface structures with three-dimensional spatial resolution. Pushing the resolution below 1 µm remains a major challenge, however, owing to the sensitivity limitations of conventional inductive detection techniques. Currently, the smallest volume elements in an image must contain at least 1012 nuclear spins for MRI-based microscopy, or 107 electron spins for electron spin resonance microscopy. Magnetic resonance force microscopy (MRFM) was proposed as a means to improve detection sensitivity to the single-spin level, and thus enable three-dimensional imaging of macromolecules (for example, proteins) with atomic resolution. MRFM has also been proposed as a qubit readout device for spin-based quantum computers. Here we report the detection of an individual electron spin by MRFM. A spatial resolution of 25 nm in one dimension was obtained for an unpaired spin in silicon dioxide. The measured signal is consistent with a model in which the spin is aligned parallel or anti-parallel to the effective field, with a rotating-frame relaxation time of 760 ms. The long relaxation time suggests that the state of an individual spin can be monitored for extended periods of time, even while subjected to a complex set of manipulations that are part of the MRFM measurement protocol.

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MAR05-2004-020060
Abstract for an Invited Paper
for the MAR05 Meeting of
the American Physical Society
Single spin detection by magnetic resonance force microscopy
DANIEL RUGAR, IBM Research Division, Almaden Research Center, San Jose, CA 95120
Single spin detection by magnetic resonance force microscopy (MRFM) is based on ultrasensitive measurements of the
attonewton magnetic force between a spin and a nearby magnetic tip. Interest in the technique is driven by potential
applications to three-dimensional atomic resolution imaging and by fundamental interest in the detection and manipulation of
individual quantum objects. This talk describes the basic principles of MRFM and discusses recent results that demonstrated
the detection of an individual electron spin buried below the surface of a silicon dioxide sample. Various innovations that led
to single spin detection will be described, including ultrasensitive force detection, spin-friendly micromechanical cantilevers
and methods to measure and control statistical polarization in small spin ensembles. Future prospects for quantum state
readout and for extension to nuclear spin detection will be discussed. This work was performed in collaboration with H. J.
Mamin, R. Budakian and B. W. Chui.
Citations
More filters
Journal Article•DOI•
Spins in few-electron quantum dots

[...]

Ronald Hanson1, Leo P. Kouwenhoven2, Jason R. Petta3, Seigo Tarucha4, Lieven M. K. Vandersypen2 •
University of California, Santa Barbara1, Delft University of Technology2, Princeton University3, University of Tokyo4
01 Oct 2007-Reviews of Modern Physics
TL;DR: In this article, the physics of spins in quantum dots containing one or two electrons, from an experimentalist's viewpoint, are described, and various methods for extracting spin properties from experiment are presented, restricted exclusively to electrical measurements.
Abstract: The canonical example of a quantum-mechanical two-level system is spin. The simplest picture of spin is a magnetic moment pointing up or down. The full quantum properties of spin become apparent in phenomena such as superpositions of spin states, entanglement among spins, and quantum measurements. Many of these phenomena have been observed in experiments performed on ensembles of particles with spin. Only in recent years have systems been realized in which individual electrons can be trapped and their quantum properties can be studied, thus avoiding unnecessary ensemble averaging. This review describes experiments performed with quantum dots, which are nanometer-scale boxes defined in a semiconductor host material. Quantum dots can hold a precise but tunable number of electron spins starting with 0, 1, 2, etc. Electrical contacts can be made for charge transport measurements and electrostatic gates can be used for controlling the dot potential. This system provides virtually full control over individual electrons. This new, enabling technology is stimulating research on individual spins. This review describes the physics of spins in quantum dots containing one or two electrons, from an experimentalist’s viewpoint. Various methods for extracting spin properties from experiment are presented, restricted exclusively to electrical measurements. Furthermore, experimental techniques are discussed that allow for 1 the rotation of an electron spin into a superposition of up and down, 2 the measurement of the quantum state of an individual spin, and 3 the control of the interaction between two neighboring spins by the Heisenberg exchange interaction. Finally, the physics of the relevant relaxation and dephasing mechanisms is reviewed and experimental results are compared with theories for spin-orbit and hyperfine interactions. All these subjects are directly relevant for the fields of quantum information processing and spintronics with single spins i.e., single spintronics.

2,389 citations

Journal Article•DOI•
Nanoscale magnetic sensing with an individual electronic spin in diamond

[...]

Jeronimo R. Maze1, Paul L. Stanwix1, Jonathan S. Hodges2, Jonathan S. Hodges1, Sungkun Hong1, Jacob M. Taylor2, Paola Cappellaro1, Liang Jiang1, M. V. Gurudev Dutt3, Emre Togan1, Alexander S. Zibrov1, Amir Yacoby1, Ronald L. Walsworth1, Mikhail D. Lukin1 •
Harvard University1, Massachusetts Institute of Technology2, University of Pittsburgh3
02 Oct 2008-Nature
TL;DR: An approach to nanoscale magnetic sensing is experimentally demonstrated, using coherent manipulation of an individual electronic spin qubit associated with a nitrogen-vacancy impurity in diamond at room temperature to achieve detection of 3 nT magnetic fields at kilohertz frequencies after 100 s of averaging.
Abstract: Detection of weak magnetic fields with nanoscale spatial resolution is an outstanding problem in the biological and physical sciences. For example, at a distance of 10 nm, the spin of a single electron produces a magnetic field of about 1 muT, and the corresponding field from a single proton is a few nanoteslas. A sensor able to detect such magnetic fields with nanometre spatial resolution would enable powerful applications, ranging from the detection of magnetic resonance signals from individual electron or nuclear spins in complex biological molecules to readout of classical or quantum bits of information encoded in an electron or nuclear spin memory. Here we experimentally demonstrate an approach to such nanoscale magnetic sensing, using coherent manipulation of an individual electronic spin qubit associated with a nitrogen-vacancy impurity in diamond at room temperature. Using an ultra-pure diamond sample, we achieve detection of 3 nT magnetic fields at kilohertz frequencies after 100 s of averaging. In addition, we demonstrate a sensitivity of 0.5 muT Hz(-1/2) for a diamond nanocrystal with a diameter of 30 nm.

1,817 citations

Journal Article•DOI•
Nanoscale imaging magnetometry with diamond spins under ambient conditions

[...]

Gopalakrishnan Balasubramanian1, I. Y. Chan2, I. Y. Chan1, Roman Kolesov1, Mohannad Al-Hmoud1, Julia Tisler1, Chang S. Shin3, Changdong Kim3, Aleksander K. Wójcik3, Philip R. Hemmer3, Anke Krueger4, Tobias Hanke5, Alfred Leitenstorfer5, Rudolf Bratschitsch5, Fedor Jelezko1, Jörg Wrachtrup1 •
University of Stuttgart1, Brandeis University2, Texas A&M University3, University of Kiel4, University of Konstanz5
02 Oct 2008-Nature
TL;DR: This work shows how magneto-optical spin detection can be used to determine the location of a spin associated with a single nitrogen-vacancy centre in diamond with nanometre resolution under ambient conditions, and demonstrates the use of a single diamond spin as a scanning probe magnetometer to map nanoscale magnetic field variations.
Abstract: Magnetic resonance imaging and optical microscopy are key technologies in the life sciences. For microbiological studies, especially of the inner workings of single cells, optical microscopy is normally used because it easily achieves resolution close to the optical wavelength. But in conventional microscopy, diffraction limits the resolution to about half the wavelength. Recently, it was shown that this limit can be partly overcome by nonlinear imaging techniques, but there is still a barrier to reaching the molecular scale. In contrast, in magnetic resonance imaging the spatial resolution is not determined by diffraction; rather, it is limited by magnetic field sensitivity, and so can in principle go well below the optical wavelength. The sensitivity of magnetic resonance imaging has recently been improved enough to image single cells, and magnetic resonance force microscopy has succeeded in detecting single electrons and small nuclear spin ensembles. However, this technique currently requires cryogenic temperatures, which limit most potential biological applications. Alternatively, single-electron spin states can be detected optically, even at room temperature in some systems. Here we show how magneto-optical spin detection can be used to determine the location of a spin associated with a single nitrogen-vacancy centre in diamond with nanometre resolution under ambient conditions. By placing these nitrogen-vacancy spins in functionalized diamond nanocrystals, biologically specific magnetofluorescent spin markers can be produced. Significantly, we show that this nanometre-scale resolution can be achieved without any probes located closer than typical cell dimensions. Furthermore, we demonstrate the use of a single diamond spin as a scanning probe magnetometer to map nanoscale magnetic field variations. The potential impact of single-spin imaging at room temperature is far-reaching. It could lead to the capability to probe biologically relevant spins in living cells.

1,814 citations

Journal Article•DOI•
Cavity Optomechanics: Back-Action at the Mesoscale

[...]

Tobias J. Kippenberg1, Kerry J. Vahala1•
Max Planck Society1
29 Aug 2008-Science
TL;DR: Recent experiments have reached a regime where the back-action of photons caused by radiation pressure can influence the optomechanical dynamics, giving rise to a host of long-anticipated phenomena.
Abstract: The coupling of optical and mechanical degrees of freedom is the underlying principle of many techniques to measure mechanical displacement, from macroscale gravitational wave detectors to microscale cantilevers used in scanning probe microscopy. Recent experiments have reached a regime where the back-action of photons caused by radiation pressure can influence the optomechanical dynamics, giving rise to a host of long-anticipated phenomena. Here we review these developments and discuss the opportunities for innovative technology as well as for fundamental science.

1,718 citations

Journal Article•DOI•
Introduction to quantum noise, measurement, and amplification

[...]

Aashish A. Clerk1, Michel Devoret2, Steven Girvin2, Florian Marquardt3, Robert Schoelkopf2 •
McGill University1, Yale University2, Ludwig Maximilian University of Munich3
15 Apr 2010-Reviews of Modern Physics
TL;DR: In this paper, a pedagogical introduction to the physics of quantum noise and its connections to quantum measurement and quantum amplification is given, and the basics of weak continuous measurements are described.
Abstract: The topic of quantum noise has become extremely timely due to the rise of quantum information physics and the resulting interchange of ideas between the condensed matter and atomic, molecular, optical--quantum optics communities. This review gives a pedagogical introduction to the physics of quantum noise and its connections to quantum measurement and quantum amplification. After introducing quantum noise spectra and methods for their detection, the basics of weak continuous measurements are described. Particular attention is given to the treatment of the standard quantum limit on linear amplifiers and position detectors within a general linear-response framework. This approach is shown how it relates to the standard Haus-Caves quantum limit for a bosonic amplifier known in quantum optics and its application to the case of electrical circuits is illustrated, including mesoscopic detectors and resonant cavity detectors.

1,581 citations

References
More filters
Frequency modulation detection using highdkantilevers for enhanced force microscope sensitivity

[...]

T. R. Albrecht, D. Horne, D. Rugar
01 Jan 2001
TL;DR: In this paper, a frequency modulation (FM) technique has been demonstrated which ennances the sensitivity of attractive mode force microscopy by an order of magnitude or more, which is made possible by operating in a moderate vacuum ( < 10 ’ Torr).
Abstract: A new frequency modulation (FM) technique has been demonstrated which ennances the sensitivity of attractive mode force microscopy by an order of magnitude or more. Increased sensitivity is made possible by operating in a moderate vacuum ( < 10 ’ Torr), which increases the Q of the vibrating cantilever. In the FM technique, the cantilever serves as the frequency determining element of an oscillator. Force gradients acting on the cantilever cause instantaneous frequency modulation of the oscillator output, which is demodulated with a FM detector. Unlike conventional “slope detection,” the FM technique offers increased sensitivity through increased Q without restricting system bandwidth. Experimental comparisons of FM detection in vacuum (Q50 000) versus slope detection in air (Q100) demonstrated an improvement of more than 10 times in sensitivity for a fixed bandwidth. This improvement is evident in images of magnetic transitions on a thin-film CoPtCr magnetic disk. In the future, the increased sensitivity offered by this technique should extend the range of problems accessible by force microscopy.

1,916 citations

Book•
An introduction to the theory of random signals and noise

[...]

Wilbur B. Davenport, William L. Root
01 Jan 1958
TL;DR: The aim of this book is to clarify the role of noise in the development of linear and nonlinear systems and to provide a procedure forormalising the noise generated by these systems.
Abstract: Preface to the IEEE Press Edition. Preface. Errata. Introduction. Probability. Random Variables and Probability Distributions. Averages. Sampling. Spectral Analysis. Shot Noise. The Gaussian Process. Linear Systems. Noise Figures. Optimum Linear Systems. Nonlinear Devices: The Direct Method. Nonlinear Devices: The Transform Method. Statistical Detection Signals. Appendix 1: The Impulse Function. Appendix 2: Integral Equations. Bibliography. Index.

1,473 citations

Journal Article•
Single-shot read-out of an individual electron spin in a quantum dot

[...]

J. M. Elzerman
25 Mar 2005-Bulletin of the American Physical Society
TL;DR: Electrical single-shot measurement of the state of an individual electron spin in a semiconductor quantum dot is demonstrated using spin-to-charge conversion of a single electron confined in the dot, and the single-electron charge is detected using a quantum point contact.
Abstract: Spin is a fundamental property of all elementary particles. Classically it can be viewed as a tiny magnetic moment, but a measurement of an electron spin along the direction of an external magnetic field can have only two outcomes: parallel or anti-parallel to the field. This discreteness reflects the quantum mechanical nature of spin. Ensembles of many spins have found diverse applications ranging from magnetic resonance imaging to magneto-electronic devices, while individual spins are considered as carriers for quantum information. Read-out of single spin states has been achieved using optical techniques, and is within reach of magnetic resonance force microscopy. However, electrical read-out of single spins has so far remained elusive. Here we demonstrate electrical single-shot measurement of the state of an individual electron spin in a semiconductor quantum dot. We use spin-to-charge conversion of a single electron confined in the dot, and detect the single-electron charge using a quantum point contact; the spin measurement visibility is ∼65%. Furthermore, we observe very long single-spin energy relaxation times (up to ∼0.85 ms at a magnetic field of 8 T), which are encouraging for the use of electron spins as carriers of quantum information.

1,087 citations

Journal Article•DOI•
Two-bit gates are universal for quantum computation

[...]

David P. DiVincenzo1•
IBM1
01 Feb 1995-Physical Review A
TL;DR: A proof is given, which relies on the commutator algebra of the unitary Lie groups, that quantum gates operating on just two bits at a time are sufficient to construct a general quantum circuit.
Abstract: A proof is given, which relies on the commutator algebra of the unitary Lie groups, that quantum gates operating on just two bits at a time are sufficient to construct a general quantum circuit. The best previous result had shown the universality of three-bit gates, by analogy to the universality of the Toffoli three-bit gate of classical reversible computing. Two-bit quantum gates may be implemented by magnetic resonance operations applied to a pair of electronic or nuclear spins. A ``gearbox quantum computer'' proposed here, based on the principles of atomic-force microscopy, would permit the operation of such two-bit gates in a physical system with very long phase-breaking (i.e., quantum-phase-coherence) times. Simpler versions of the gearbox computer could be used to do experiments on Einstein-Podolsky-Rosen states and related entangled quantum states.

1,073 citations

Journal Article•DOI•
The principles of magnetic resonance

[...]

D B Longmore
01 Oct 1989-British Medical Bulletin
TL;DR: The simplified description of the phenomena involved in MR is intended to be comprehensive and does not require foreknowledge of classical physics, quantum mechanics, fluency with mathematical formulae or an understanding of image reconstruction.
Abstract: Magnetic Resonance (MR), which has no known biological hazard, is capable of producing high resolution thin tomographic images in any plane and blocks of 3-dimensional information. It can be used to study blood flow and to gain information about the composition of important materials seen and quantified on dimensionally accurate images. The MR image is a thin tomographic slice or a true three dimensional block of data which can be reconstructed in any desired way rather than a shadowgram of all the structures in the beam. It is the only imaging technique which can acquire data in a 3-dimensional format. CT images can be reconstructed to form a pseudo 3-D image or a hologram but the flexibility conferred by acquiring the data as a true 3-D block gives many advantages. The spatial resolution of MR images are theoretically those of low powered microscopy, the practical limits with the present generation of equipment are voxel sizes of one third by one third by two millimetres. The term Magnetic Resonance Imaging (MRI) is used commonly, particularly in the USA, avoiding association with the term, nuclear, and emphasizing the imaging potential of the technique. The terms Nuclear Magnetic Resonance (NMR) or Magnetic Resonance (MR) more correctly describe the most powerful diagnostic instrument yet devised. The simplified description of the phenomena involved in MR which follows is intended to be comprehensive and does not require foreknowledge of classical physics, quantum mechanics, fluency with mathematical formulae or an understanding of image reconstruction. There are many explanations of MR, some omitting the more difficult concepts. An accurate, comprehensive description is found on the textbook on MR by Gadian, Nuclear Magnetic Resonance and its Applications for Living Systems (Oxford University Press, 1982).

906 citations

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