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

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Shot NoiseDC current through a resistor vs. time

Discrete/Quantized nature of transport!

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Quantifying Noise

⟨(δ I )2⟩=∫ Sδ I ( f )df

Noise Power Spectral Density

Current fluctuation

δ I=I−⟨ I ⟩

Sδ I ( f )

δ I

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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.

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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.

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Interacting Systems

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Interacting SystemsNormal metal/superconductor junction

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

2 e

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Interacting SystemsFractional Quantum Hall Effect

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

e /3

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Shot Noise

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Spin Currents

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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).

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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

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Magnon

Considering only exchange interaction and Zeeman energy!

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

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Magnon

+

ℏ

Considering only exchange interaction and Zeeman energy!

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

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Ferromagnet Eigenmodes

With magnon annihilation operators

Effect of dipolar interactions!

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

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Squeezed-magnons


Bogoliubov transformation to new quasi-particles

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Spin Current Injection

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Ferromagnetic Resonance

Under coherent excitation

Resonant excitation of the uniform mode and spin current injection!

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Spin Current Shot Noise

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Squeezed-magnon


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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

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Squeezed-magnon

What's in the name – relation to squeezed light

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

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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).

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Finite Temperature Noise

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



0.1 1 10 10010 17

10 18

10 19

10 20

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0.1 1 10 10010 17

10 18

10 19

10 20

0.1 1 10

10 12

10 14

10 16

10 18

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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).

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

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