super-poissonian shot noise of squeezed- magnon … · super-poissonian shot noise of...

Super-Poissonian shot noise of squeezed-magnon mediated spin transport

Akashdeep Kamra and Wolfgang BelzigFachbereich Physik, Universität Konstanz,

D-78457 Konstanz, Germany

Reference: Phys. Rev. Lett. 116, 146601 (2016).

Akashdeep Kamra Uni Konstanz 15th April 2016

Akashdeep Kamra Uni Konstanz

What's that noise!DC current through a resistor vs. time

15th April 2016

Akashdeep Kamra Uni Konstanz

What's that noise!DC current through a resistor vs. time

15th April 2016

Akashdeep Kamra Uni Konstanz

What's that noise!DC current through a resistor vs. time

15th April 2016

Akashdeep Kamra Uni Konstanz

What's that noise!DC current through a resistor vs. time

15th April 2016

Akashdeep Kamra Uni Konstanz

Shot NoiseDC current through a resistor vs. time

Discrete/Quantized nature of transport!

15th April 2016

Akashdeep Kamra Uni Konstanz

Quantifying Noise

⟨(δ I )2⟩=∫ Sδ I ( f )df

Noise Power Spectral Density

Current fluctuation

δ I=I−⟨ I ⟩

Sδ I ( f )

δ I

15th April 2016

Akashdeep Kamra Uni Konstanz

Poissonian Transport

Y. V. Nazarov and Y. M. Blanter, Quantum Transport Introduction to Nanoscience (Cambridge University Press, 2009).

Probability rate of a charge transfer event is constant.

15th April 2016

Akashdeep Kamra Uni Konstanz

Poissonian Transport

Y. V. Nazarov and Y. M. Blanter, Quantum Transport Introduction to Nanoscience (Cambridge University Press, 2009).

Probability rate of a charge transfer event is constant.

15th April 2016

Akashdeep Kamra Uni Konstanz

Poissonian Transport

Y. V. Nazarov and Y. M. Blanter, Quantum Transport Introduction to Nanoscience (Cambridge University Press, 2009).

S (0)=2 q ⟨ I ⟩Probability rate of a charge transfer event is constant.

15th April 2016

Akashdeep Kamra Uni Konstanz

Interacting Systems

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Akashdeep Kamra Uni Konstanz

Interacting SystemsNormal metal/superconductor junction

X. Jehl, M. Sanquer, R. Calemczuk, and D. Mailly, Nature 405, 50 (2000).

2 e

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Akashdeep Kamra Uni Konstanz

Interacting SystemsFractional Quantum Hall Effect

L. Saminadayar, D. C. Glattli, Y. Jin, and B. Etienne, Phys. Rev. Lett. 79, 2526 (1997).

e /3

15th April 2016

Akashdeep Kamra Uni Konstanz

Shot Noise

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Akashdeep Kamra Uni Konstanz

Spin Currents

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Akashdeep Kamra Uni Konstanz

Spin CurrentsFerromagnetic insulator (FI)/non-magnetic metal (N)

e

e

e

e

ee

e

e

e

e

e

e

e

e

e

e

e

e

e

e

e

e

e

ee

e

eee e

e

e

e

e

e

e

e

e

e

e

e

e

V. V. Kruglyak, S. O. Demokritov, and D. Grundler, Journal of Physics D: Applied Physics 43, 264001 (2010).

15th April 2016

Akashdeep Kamra Uni Konstanz

Thermal Spin Current NoiseFerromagnetic insulator (FI)/non-magnetic metal (N)

A. Kamra, F. P. Witek, S. Meyer, H. Huebl, S. Geprägs, R. Gross, G. E. W. Bauer, and S. T. B. Goennenwein, Phys. Rev. B 90, 214419 (2014).

y y

4268

4270

4272

4274

4276YIG(60nm)|Pt(2.2nm) 291.5K

Rlo

ng

()

0 90 180 270 360

6.870

6.873

6.876

6.879

6.882

SV

,lon

g(V

2/H

z)

(°)

x10-17

Pt YIG GGG

15th April 2016

Akashdeep Kamra Uni Konstanz

Magnon

Considering only exchange interaction and Zeeman energy!

C. Kittel, Introduction to Solid State Physics (John Wiley & Sons, New York, 1953)

15th April 2016

Akashdeep Kamra Uni Konstanz

Magnon

Considering only exchange interaction and Zeeman energy!

C. Kittel, Introduction to Solid State Physics (John Wiley & Sons, New York, 1953)

15th April 2016

Akashdeep Kamra Uni Konstanz

Magnon

+

ℏ

Considering only exchange interaction and Zeeman energy!

C. Kittel, Introduction to Solid State Physics (John Wiley & Sons, New York, 1953)

15th April 2016

Akashdeep Kamra Uni Konstanz

Ferromagnet Eigenmodes

With magnon annihilation operators

Effect of dipolar interactions!

T. Holstein and H. Primakoff, Phys. Rev. 58, 1098 (1940).

15th April 2016

Akashdeep Kamra Uni Konstanz

Squeezed-magnons

T. Holstein and H. Primakoff, Phys. Rev. 58, 1098 (1940).

Bogoliubov transformation to new quasi-particles

15th April 2016

Akashdeep Kamra Uni Konstanz

Spin Current Injection

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Akashdeep Kamra Uni Konstanz

Ferromagnetic Resonance

Under coherent excitation

Resonant excitation of the uniform mode and spin current injection!

15th April 2016

Akashdeep Kamra Uni Konstanz

Spin Current Shot Noise

15th April 2016

Akashdeep Kamra Uni Konstanz

Spin Current Shot Noise

15th April 2016

Akashdeep Kamra Uni Konstanz

Squeezed-magnon

T. Holstein and H. Primakoff, Phys. Rev. 58, 1098 (1940).

15th April 2016

Akashdeep Kamra Uni Konstanz

Squeezed-magnon

0 0.1 0.2 0.3 0.4 0.50

1

2

3

4

5

6

7

0

5

10

15

20

25

30

35

0 0.1 0.2 0.3 0.4 0.50

0.5

1

1.5

2

0

5

10

15

20

Specimens in the shape of films

15th April 2016

Akashdeep Kamra Uni Konstanz

Squeezed-magnon

What's in the name – relation to squeezed light

C. Gerry and P. Knight, Introductory Quantum Optics (Cambridge University Press, 2005).

15th April 2016

Akashdeep Kamra Uni Konstanz

Squeezed-magnon

What's in the name – relation to squeezed light

C. Gerry and P. Knight, Introductory Quantum Optics (Cambridge University Press, 2005).

15th April 2016

Akashdeep Kamra Uni Konstanz

Squeezed-magnon

What's in the name – relation to squeezed light

Two mode squeezing

C. Gerry and P. Knight, Introductory Quantum Optics (Cambridge University Press, 2005).

15th April 2016

Akashdeep Kamra Uni Konstanz

Finite Temperature Noise

15th April 2016

A. Kamra and W. Belzig, arXiv:1604.02079 [cond-mat.mes-hall]

Akashdeep Kamra Uni Konstanz

Finite Temperature Noise

0.1 1 10 10010 17

10 18

10 19

10 20

15th April 2016

A. Kamra and W. Belzig, arXiv:1604.02079 [cond-mat.mes-hall]

Akashdeep Kamra Uni Konstanz

Finite Temperature Noise

0.1 1 10 10010 17

10 18

10 19

10 20

15th April 2016

A. Kamra and W. Belzig, arXiv:1604.02079 [cond-mat.mes-hall]

Akashdeep Kamra Uni Konstanz

Finite Temperature Noise

0.1 1 10 10010 17

10 18

10 19

10 20

0.1 1 10

10 12

10 14

10 16

10 18

15th April 2016

A. Kamra and W. Belzig, arXiv:1604.02079 [cond-mat.mes-hall]

Akashdeep Kamra Uni Konstanz

Summary

● Dipolar interaction mediated squeezing of magnons

● Non-integer spin of squeezed-magnons● Dominance of shot over thermal noise● Quantum properties associated with squeezing

Reference: Phys. Rev. Lett. 116, 146601 (2016).

15th April 2016