Excitons in Electrostatic Lattices M. Remeika 1 , L.V. Butov 1 , M. - - PowerPoint PPT Presentation

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Excitons in Electrostatic Lattices M. Remeika 1 , L.V. Butov 1 , M. Hanson 2 , A.C. Gossard 2 1 University of California San Diego, Department of Physics 2 University of California, Santa Barbara, Materials Department APS March Meeting 2011

SLIDE 1

Excitons in Electrostatic Lattices

M. Remeika1, L.V. Butov1 , M. Hanson2, A.C. Gossard2

1University of California San Diego, Department of Physics 2University of California, Santa Barbara, Materials Department

APS March Meeting 2011

SLIDE 2

Indirect Excitons

More about indirect excitons: Excitons in moving lattices

J. Leonard, 10:24 AM, Wednesday

Room C144, P32

Excitation energy dependence of the exciton inner ring

Y. Kuznetsova, 12:39 AM, Friday,

Room D163, Z22

Spin Texture in a Cold Exciton Gas

A. High, 10:48 AM, Friday,

Room D171, Y15

Excitons in Electrostatic Lattices Slide 2/9

d Indirect Exciton Energy is controlled by applied voltage: Bound pair of an electron and a hole confined to separate quantum wells

SLIDE 3

Depth controlled in-situ by voltage

High speed control

Structure determined by electrode pattern

Arbitrary lattice structures
Compatible with

semiconductor processing technology

Exciton number controlled by laser power

Selective loading to individual

lattice sites

Electrostatic Lattice for Indirect Excitons

Another system with many controllable parameters: cold atoms in optical lattices

Cold particles
Tunable lattice depth
Could emulate properties of

condensed matter systems

Excitons in Electrostatic Lattices Slide 3/9

Other controlled parameters

Interaction strength
Effective mass
Exciton lifetime
Exciton temperature

Excitons can cool down below temperature of quantum degeneracy

SLIDE 4

Excitons in an Electrostatic Lattice

M. Remeika, J. C. Graves, A. T. Hammack, A. D. Meyertholen, M. M. Fogler, L. V. Butov, M. Hanson,
A. C. Gossard PRL, 102,186803 (2009)

Excitons in Electrostatic Lattices Slide 4/9

Linear Lattice

SLIDE 5

Two Dimensional Lattice

Two Dimensional Lattice Design

Excitons in Electrostatic Lattices Slide 5/9

Linear Lattice

Square Triangular Honeycomb

High Low

Uex

Different lattice structures
Onsite interaction (dipole blockade – Coulomb blockade)

SLIDE 6

Two Dimensional Lattice Design

Excitons in Electrostatic Lattices Slide 6/8

Method of Potential Control by Electrode Density

Y. Y. Kuznetsova, A. A. High,
L. V. Butov APL, 97, 201106 (2010)
22meV

Exciton Energy

Applied to a Lattice Potential:

Lattice structure determined by electrode

design

Independently controlled lattice depth

and base energy

Electrode pattern fabricated in a single

lithography step

2μm Parabolic Potential

34meV

V2 V1 V2=-2V V1=-4V Snowflake trap

SLIDE 7

5μm

Excitons in Electrostatic Lattices Slide 7/9

SEM Images

Square Triangular Honeycomb

SLIDE 8

Preliminary Data on Excitons in a 2D Lattice

Excitons in Electrostatic Lattices Slide 8/9

High Energy Emission Low Energy Emission

Work in progress

1 10 100 1000 1.535 1.540 1.545 1.550

0 meV 0.8 meV 1.7 meV 2.5 meV 3.4 meV 4.2 meV

Laser Power (W)

Emission Energy (eV) Controlled by voltage Controlled by voltage Measured by exciton energy shift Measured by exciton energy shift Linear lattice

SLIDE 9

Conclusions

Developed a method to create 2D electrostatic

lattices for excitons.

Realized square, triangular, and honeycomb lattices.
Analysis of exciton localization-delocalization

transition as a function of exciton density and lattice amplitude is in progress.

Excitons in Electrostatic Lattices Slide 9/9