Magnetic Resonance with Single Nuclear-Spin Sensitivity Alex - PowerPoint PPT Presentation

1 Magnetic Resonance with Single Nuclear-Spin Sensitivity Alex Sushkov

2 MRI scanner $2 million 7 tons 1500 liters of He

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4 5 µm magnetic force microscopy (MFM) image of hard drive surface topological spin texture in helical magnet Fe 0.5 Co 0.5 Si [Nature 465, 901 (2010)]

5 Magnetic sensors sensitivity resolution MRFM SERF number of detectable Nature 422, 596 (2003) Science 264, 1560 (1994) magnetic moments (spins) SQUID scanning SQUID Phys.Rev.Lett. 12, 159 (1964) Appl.Phys.Lett . 61, 598 (1992)

6 The challenge: detecting a single proton spin the ultimate limit of magnetization sensitivity 𝐶 𝑜 ≈ 𝜈 𝑜 /𝑠 3 closer is better

7 Taking magnetic sensing to the nanoscale

8 Taking magnetic sensing to the nanoscale

9 Taking magnetic sensing to the nanoscale

10 Outline 1. The NV color center in diamond: introduction and applications 2. Magnetic sensing with an NV center: the tools 3. NMR experiments with liquid hydrocarbons: detecting 10 4 nuclear spins 4. NMR spectroscopy of single protein molecules: detecting 400 nuclear spins 5. NMR with single nuclear spin sensitivity 6. Outlook

11 Nitrogen-vacancy (NV) centers in diamond Nitrogen impurity next to a vacancy inside the diamond lattice behaves like a single atom trapped inside the transparent diamond crystal

12 Making NV centers in diamond “electronic - grade” diamond crystal 1. 2. nitrogen ion implantation 3. anneal at 800 C behaves like a single atom trapped inside the transparent diamond crystal

13 Properties of NV centers in diamond 1. the relevant levels of the NV center are within diamond bandgap, an electric-dipole transition

14 Properties of NV centers in diamond 1. the relevant levels of the NV center are within diamond bandgap, an electric-dipole transition 2. ground-state electron spin S=1

15 Properties of NV centers in diamond 1. the relevant levels of the NV center are within diamond bandgap, an electric-dipole transition 2. ground-state electron spin S=1

16 Properties of NV centers in diamond 1. the relevant levels of the NV center are within diamond bandgap, an electric-dipole transition 2. ground-state electron spin S=1 a two-level system

17 A schematic sensing experiment with an NV center 1. the relevant levels of the NV center are within diamond bandgap, an electric-dipole transition 2. ground-state electron spin S=1 equal populations at room temperature

18 A schematic sensing experiment with an NV center 1. the relevant levels of the NV center are within diamond bandgap, an electric-dipole transition 2. ground-state electron spin S=1 3. optical initialization of spin state optical pumping

19 A schematic sensing experiment with an NV center 1. the relevant levels of the NV center are within diamond bandgap, an electric-dipole transition 2. ground-state electron spin S=1 3. optical initialization of spin state 4. optical readout of spin state less fluorescence more fluorescence

20 A schematic sensing experiment with an NV center 1. the relevant levels of the NV center are within diamond bandgap, an electric-dipole transition 2. ground-state electron spin S=1 3. optical initialization of spin state 4. optical readout of spin state 5. microwave manipulation of spin state microwave drive

21 A schematic sensing experiment with an NV center ESR spectroscopy less fluorescence more fluorescence

22 A schematic sensing experiment with an NV center Rabi oscillations less fluorescence more fluorescence a room-temperature single- spin quantum system

23 Experimental apparatus RF transmission line on a glass coverslip ≈ 5 nm ambient conditions 532 nm laser beam oil-immersion microscope objective permanent magnet

24 Applications of NV centers quantum nuclear spins registers Science 336 , 1283 (2012) quantum metrology • magnetic fields networks • nanophotonics • electric fields • mechanical • temperature resonators • gyroscopes Nature 466 , 730 (2010) Nature Physics 4 , 810 (2008) Nature 497 , 86 (2013) Science 339 , 561 (2013) Science 335 , 1603 (2012) Nature Physics 7 , 459 (2011) Nature 500 , 54 (2013) Phys. Rev. A 86 , 0521226 (2012) Physics Today 67 , 38 (2014) Scientific American 297 , 84 (2007)

25 Outline 1. The NV color center in diamond: introduction and applications 2. Magnetic sensing with an NV center: the tools

26 NV-based magnetic sensing schemes population and coherence of ground-state sublevels • fast-oscillating fields (>GHz)  NV population transfer (incoherent) all-optical magnetic detection of single-atom Gd spins at room temperature Alex Sushkov, Nick Chisholm, Igor Lovchinsky, et al., Nano Lett . 14 , 6443 (2014) probing magnetic Johnson noise at the nanometer scale, electron ballistic transport Shimon Kolkowitz, Arthur Safira, et al., Science, in press

27 NV-based magnetic sensing schemes population and coherence of ground-state sublevels • fast-oscillating fields (>GHz)  NV population transfer (incoherent) • radiofrequency fields (kHz – 100 MHz)  NV echo magnetometry (coherent) B n B 0 Larmor precession of a nuclear spin: time

28 NV spin echo magnetic sensing static or slowly-varying magnetic field  optical 𝜒 1 ∝ 𝐶 𝑜 𝜐 𝜒 2 ∝ −𝐶 𝑜 𝜐 fluorescence pumping spin readout into m s =0 𝜒 1 + 𝜒 2 = 0

29 NV spin echo magnetic sensing oscillating magnetic field  optical 𝜒 1 ∝ 𝐶 𝑜 𝜐 𝜒 2 ∝ −(−𝐶 𝑜 )𝜐 fluorescence pumping spin readout into m s =0 𝜒 1 + 𝜒 2 ∝ 2𝐶 𝑜 𝜐 spin echo sensitive to magnetic fields at frequencies ~𝟐/𝟑𝝊

30 NV CPMG (Carr-Purcell-Meiboom-Gill) magnetic sensing NV center spin  magnetic spectrometer optical fluorescence pumping spin readout into m s =0 • robust against pulse errors • longer NV T 2 due to dynamical decoupling from environment spectral selectivity by varying free evolution interval  •

31 Outline 1. The NV color center in diamond: introduction and applications 2. Magnetic sensing with an NV center: the tools 3. NMR experiments with liquid hydrocarbons: detecting 10 4 nuclear spins

32 An NV-based NMR experiment target sample with nuclear spins randomly-oriented proton spins add to give zero net magnetic field: 𝐶 𝑜 = 0 but there is a “statistical polarization” ~ 𝑂 2 ≠ 0 𝐶 𝑜 2 measure variance of nuclear magnetic field: 𝐶 𝑜

33 First NMR experiments: protons in immersion oil NV magnetometry measures magnetic field B n from proton spins in objective oil proton spins depth XY-32 depth = (8.2 ± 0.1) nm detecting ≈ 10 4 nuclear spins NV depth extracted from proton peak magnitude S. DeVience, L.Pham, I. Lovchinsky, et al., H. Mamin, et al., Science 339 , 557 (2013) Nature Nano , DOI: 10.1038 (2015) T. Staudacher et al., Science 339 , 561 (2013)

34 Outline 1. The NV color center in diamond: introduction and applications 2. Magnetic sensing with an NV center: the tools 3. NMR experiments with liquid hydrocarbons: detecting 10 4 nuclear spins 4. NMR spectroscopy of single protein molecules: detecting 400 nuclear spins

35 Experimental sensitivity parameters optical 𝜒 2 ∝ −(−𝐶 𝑜 )𝜐 𝜒 1 ∝ 𝐶 𝑜 𝜐 fluorescence pumping spin readout into m s =0 𝜒 1 + 𝜒 2 ∝ 2𝐶 𝑜 𝜐 2 ≈ 𝜈 𝑜 2 /𝑠 6 𝐶 𝑜 signal: closer is better 2𝜐 ≈ 𝑈 2 NV spin coherence time: longer 𝑈 2 is better NV spin readout fidelity higher fidelity is better

36 Coherence times of shallow NV centers O H shallow NV centers display likely due to surface electron C faster decoherence spins (dangling bonds) anneal diamond at 465 C in oxygen atmosphere 10-fold improvement in T 2 Igor Lovchinsky, Alex Sushkov, Elana Urbach, Nathalie de Leon, et al. manuscript in preparation

37 NV spin readout optical fluorescence pumping spin readout  | 0 measurement result is stored optical readout destroys NV electron spin state  | 0 in the NV electron spin state: α| 0 + 𝛾| −1 how well did we measure α, 𝛾 ? poor fluorescence < 1% fidelity collection efficiency

38 Improving NV spin readout using quantum logic electron J=1 15 N nuclear I=1/2  hyperfine: 𝐼 = 𝐵𝑲 ∙ 𝑱 electron spin | −1 𝐵 ≈ 3 MHz CNOT gate: flip electron spin 2.87 GHz conditional on nuclear spin state | 0 SWAP electron spin state | | ↓ ↑ with nuclear spin state: nuclear spin α 0 + 𝛾 −1 → 𝛽| ↓ + 𝛾| ↑ nuclear spin state is NOT repetitive readout D. Hume, et al., destroyed by optical excitation Phys. Rev. Lett . 99 , 120502 (2007)

39 Improving NV spin readout using quantum logic | 0 | 𝑓 | 𝑜 SWAP repetitive readout | e ↔ | n of 15 N nuclear spin improved NV spin readout efficiency by × 30 Igor Lovchinsky, Alex Sushkov, Elana Urbach, Nathalie de Leon, et al. manuscript in preparation

40 Single ubiquitin proteins ubiquitin protein, enriched with 13 C (I=1/2) and 2 H (I=1) covalent attachment of ubiquitin protein to diamond surface: AFM of a clean diamond surface: AFM of a diamond surface with attached proteins: