A cold atom source for BEC microscopy based on a five-beam MOT

kitefleaΠολεοδομικά Έργα

15 Νοε 2013 (πριν από 4 χρόνια και 1 μήνα)

73 εμφανίσεις

A cold atom source for BEC microscopy

based on a five
-
beam MOT


Robert
Hollenstein
, Christian
Koller
, Bo Lu, Jessica Maclean,
Samanta

Piano, and Peter
Krüger

University of Nottingham, University Park, Nottingham NG7 2RD, U.K.

















5

beam

MOT



Vertical

Beam

reflected

in

itself



Gold

coated

quarter
-
wave
-
plate

to

reflect

that

beam



Polarisation

for

trapping

correct

because

of

this

quarter
-
wave
-
plate




Low

reflectivity

samples



Magnetic

trap

conveyer

belt

performed

by

a

PCB

transport

following

the

design

by

Long

et

al
.

Eur
.

Phys
.

J
.

D

35
,

125

133

(
2005
)



Our setup

Apparatus under construction

Magnetic field microscopy

Coated quarter
-
wave
-
plate



MOT comparison


Advantages:


No reflective chip Surface needed


Magnetic field not rotated


generated by external coils


or a simple underlying PCB


MOT centre can be further away from the
chip surface


Disadvantages:


Gold coated lambda/4


plate to reflect the
centre beam and adjust polarisation


Area of the chip with the lambda/4 plate is
not useable for experiments


Requires transport from MOT to Sample
area


Beam is reflected inside UHV, components
need to be UHV compatible


Advantages:


Commonly used


MOT, magnetic trap and chip trap all at
same position


Disadvantages:


Requires highly reflecting chip


Magnetic field turned by 45 degrees



achieved by sophisticated
substructure


or bulky Coils which hinder
optical access


Distance to trap centre from surface fixed
by geometry


Chamber must meet requirements for
beam access

To

trap

atoms

in

a

MOT

the

laser

beams

need

to

have

the

right

polarisation

respective

to

the

local

magnetic

field
.

To

achieve

this

in

a

5

beam

setup

the

laser

travels

through

the

quarter
-
wave
-
plate,

is

reflected

at

the

back

and

travels

through

the

plate

again
.


For

implementing

this

onto

a

chip

we

coated

a

quarter
-
wave
-
plate

with

highly

reflecting

gold

as

a

mirror
.

This

quarter
-
wave
-
plate

is

then

mounted

on

top

of

the

chip
.


Magnetic

field

microscopy

using

cold

atoms

is

an

extremely

sensitive

technique

(down

to

4
nT)

with

a

high

resolution

(down

to

3
µm)
.

A

1
D
-
BEC

is

brought

close

to

a

specimen,

the

variation

in

the

magnetic

field

deforms

the

trapping

potential,

which

alters

the

density

distribution

of

the

BEC
.

Therefore

the

magnetic

field

distribution

over

the

whole

cloud

can

be

determined

in

a

single

shot
.

45 Degree Setup

5 Beam Setup



Test quarter
-
wave
-
plate in
Vacuum


Further optimization of the
MOT parameters


Testing

of

2
-
colour
-
Trap


Build

chip



Build

PCB


Build

mounting


Next steps

Quarter
-
wave
-
plate coated
with 200nm of Au on one side
by Physical
Vapor

Deposition

Wildermuth et al.

Appl. Phys. Lett. 88,
264103 (06)

BEC

microscopy

is

one

of

the

most

promising

routes

to

establish

quantum

technology

based

on

ultra
-
cold

atomic

systems
.

Offering

an

unmatched

balance

between

spatial

resolution

and

sensitivity

this

magnetic

field

sensing

technique

will

offer

new

insights

in

the

study

of

a

multitude

of

systems,

reaching

from

spintronics
,

superconductors

and

novel

magnetic

materials

to

biological

samples

and

graphene
.

On

this

poster

we

present

details

of

the

main

chamber

of

a

novel

experimental

setup,

which

will

act

as

a

source

for

ultra
-
cold

atoms

for

high

precision

BEC

microscopy

as

well

as

a

dedicated

platform

for

first

experiments

on

ultra
-
thin

membranes

and

magnetic

samples
.


Motivation

Join
Midlands
Ultracold

Atom Research Centre

Join us:

-

(Paid) Interns/summer projects

-

Diploma/Master projects

-

PhD positions (MC action)

-
Postdocs

Research interests:

-

Ultracold

gases in atom chips

-

Quantum interfaces

(atom
-
solid,atom
-
photon)

-

Hybrid Quantum Systems

-

BEC microscopy

http://mpa.ac.uk/muarc/


For further information contact:

-

Peter.Kruger@nottingham.ac.uk

-

Christian.Koller@nottingham.ac.uk

http://bit.ly/id0ZkM

First

measurements

of

our

5

beam

MOT

during

optimisation

show

comparable

results

to

a

standard

6

beam

MOT
.

The

current

in

the

legend

is

the

current

in

the

external

coils

which

produce

the

quadrupole

field
.

Parameters
:


Total laser intensity:

around 40mW/cm^2 (detuning
dependant)


Background Pressure:

1.1x10^
-
10mBar