Michael Wolf, Robert Badea and Jesse Berezovsky

Physics Department, Case Western Reserve University, Cleveland, OH 44106

We acknowledge DOE, grant No. DE-SC0008148

Fast nanoscale addressability of individual NV spins via coupling to

driven ferromagnetic vortices

Reflectance

2 μm

Introduction

• Diamond nanoparticles with NVs are dispersed on a gold coplanar waveguide

(CPW) with fabricated ferromagnetic disks.

• A scanning microscopy set-up is used to initialize and detect NV spins and

image magnetization.

• The disk is magnetized in a single vortex domain.

• The vortex core position is controlled by an applied magnetic field.

• See poster on Wednesday for more detail.

Magnetization maps

• BCPW is capable of translating the

vortex within tens of ns over several

hundreds of nm.

• Vortex magnetic field near the

surface of the disk can reach several

hundred mT.

OD

MR

(a.u

.)

1

0.85

0

2

4

6

8

10 B

x (

mT

)

Microwave field enhancement

Bx = 0 mT Bx = 5 mT Bx = 9 mT X

Y

MOKE

Laser

Spec. EMCCD

AOM

PM

T

PMT

TCSPC

2.5

μm

2.5 μm 20 μm

20

μm

Permalloy disk

Diamond nanoparticle

with several NVs

BCPW

Gold CPW

X

Y

Ph

oto

lum

inescen

ce (

a.u

.)

2.8 3 3.2

• Simulated ODMR of two NVs

coupled to vortex.

• NVs 10 nm apart, 20 nm

above vortex.

• Significant splitting between

the two NVs.

0 100 200 300 MW pulse length (ns)

1

0.93

0.96

Re

l. P

L (

a.u

.)

Laser

CPW

MW

• Rabi oscillations are measured by varying the MW

pulse length with constant BCPW.

• Large enhancement of the Rabi frequency at some

vortex positions.

• Enhancement largest with vortex close to NVs.

0 2 -2

Bx (m

T)

Rab

i F

req

ue

ncy

enh

an

cem

ent

Fast NV addressability

• Spin rotated to B1 direction

via adiabatic passage

• Relaxation into resonance with MW field yields

high fidelity π/2 rotation (‘adiabatic half

passage’).

• AHP aligns spin with MW field in the rotating

frame (B1).

• Subsequent manipulation possible with phase-

shifted MW field (B1’ in the rotating frame). B1 B1’

S

Ferromagnetic vortex domains produce strong, localized, rapidly-

tunable magnetic fields which may be useful for nanoscale spintronic or

quantum information processing devices. A vortex interacting with

adjacent NV spins provides a platform for addressing individual spins

for coherent manipulation or coupling. Here, we show that this

interaction leads to large spin splitting, enhancement of microwave

fields and spin manipulation via adiabatic passage.

Magneto-optical Kerr effect

Experimental set-up

Vortex-induced spin splitting

2.6

1

-1

0

0 150 300 450

CPW pulse length (ns)

Spin

pro

jection

Micromagnetic OOMMF simulation

Frequency (GHz)

Vortex

path NVs

• Sweep vortex past

nanoparticle with several

NVs.

• Monitor NV spin spitting via

optically detected magnetic

resonance (ODMR).

• Large splitting when vortex

is near NVs.

• Broadening caused by

vortex induced MW field

enhancement.

• Jumps occur to vortex

pinning (see poster on

Wednesday).

BAC = 175 μT

2.6 2.8 3 3.2

Frequency (GHz)

0

2

4

6

8

10

Bx (

mT

)

No vortex

• At B1 NV1 is in resonance with fMW

• At B2 NV2 is in resonance with fMW

• At B12 NV1 and NV2 are in

resonance with each other but not

with fMW.

Pulsing between B1, B2,

and B12 allows operations

on NV1 and NV2.

BC

PW

(mT

)

2

1

-1

-2

0

2.6 2.8 3 3.2

Frequency (GHz)

NV1

NV2

B2

B12

B1

fMW

BAC = 15 μT

BC

PW

(mT

)

2

1

-1

-2

0

2.6 2.8 3 3.2 Frequency (GHz)

Bx = 2 mT

Vortex

path NVs

Laser

CPW

MW

MW pulse length (ns) 0 150 300

Re

l. P

L (

a.u

.)

BAC= 500 μT

Pulse the vortex position to bring a

particular NV into resonance.

Method 1: Move vortex then manipulate spin

Method 2: Move vortex while manipulating spin (adiabatic passage)

0 100 200 300 MW pulse length (ns)

1

0.96

Rel. P

L (

a.u

.)

0.92

0.98

0.94

Laser

CPW

MW

• Confirmed coherence by observing

Rabi oscillations about B1’

AHP to B1 Rabi about B1’

Laser

CPW B1

B1’

0 100 200 300 MW pulse length (ns)

1

0.96

Rel. P

L (

a.u

.)

0.92

0.98

0.94

• Vortex relaxes after voltage step in ≈100ns.

• MW pulse begins 100ns after CPW step.

• Minimal reduction in oscillation amplitude.

-2

0

2

4

30

0

Vortex position

MO

KE

0

By (mT)