Transportable optical clocks: Towards gravimetry based on the - - PowerPoint PPT Presentation

Space Optical Clocks (SOC)

Transportable optical clocks: Towards gravimetry based on the gravitational redshift

• !!"#

$%&&'( &)*&)&09

Evolution of atomic clocks

Review: e. g. P. Gill, Metrologia (2005)

, Ca

Optical Optical Clocks Clocks Microwave Microwave clocks clocks Relative Uncertainty

10-9 10-10 10-11 10-12 10-13 10-14 10-15 10-16

Hg+ Al+

10-17 10-18 1950 1960 1970 1980 1990 2000 2010

Year

• Mikrowave clocks: ~ 9 GHz

Mikrowave clocks: ~ 9 GHz Optical clocks: ~ 400 000 GHz Optical clocks: ~ 400 000 GHz

Yb+ Cs fountains Sr Yb+

Single-ion trap (PTB) Neutral atom ensemble (HHUD)

Sr

Applications of Optical Clocks

• !"#

"

• $

⇒

• %&

r1 – r2 = 1 cm ⇒

• %
• "

'()*+,*- √s )

The gravitational frequency shift

18

10 ν ν

−

∆ =

1 2 1 2 2

( ) ( ) U r U r c ν ν ν − − =

gravitational potential

ν ν ν ν1

1 1 1

ν ν ν ν2

2 2 2

r1 r2

U

• Frequency comparison by: - Free-space link (~ 10 km)
• Optical fiber (~ 100 km)
• Transponder (any distance, intercontinental)
• Optical or microwave link possible
• Two-way link permits Doppler cancellation

Differential measurement

• f the gravitational potential

Transponder

• Comparison with a reference clock („master clock“)
• Possible location of „master clock“: geostationary orbit (low uncertainty of U)

Absolute measurement

• f the gravitational potential

U

Master clock (ν1)

Probe clock Probe clock Probe clock

Optical lattice clock – operating scheme

metastable state narrow transition (optical clock)

Optical lattice clock development within SOC

461 nm

(5s ) S

1 2

(5s5p) P

1 1 689 nm

698 nm

(5s5p) P

3 J

1 2

.

/01.2.3#0

398 nm

(6s ) S

1 2

(6s6p) P

1 1 556 nm

578 nm

(6s6p) P

3 J

1 2

3

44!5 clock transition

LENS HHUD

5

• Ultracold atom source

Frequency Control system Frequency Control system

Clock Laser Clock Laser

Lattice

Strontium optical lattice clock - setup

Laboratory source of ultracold atoms (partial view)

SYRTE

Clock laser

PTB

vibration-insensitive cavity

Clock transition spectroscopy

Strontium optical lattice clock - performance

6' Sr clock frequency: 429 228 004 229 873.6 Hz 0)'

SYRTE SYRTE

Lowest systematic uncertainty: 1 x 10-16 (JILA/NIST)

Ludlow et al., Science (2008)

Strontium optical lattice clock - accuracy budget

Compact clock apparatus - Yb

„Blue“ laser

system (399 nm) Lattice laser (759 nm) „Green“ laser (556 nm) Main chamber Spectroscopy beam

• !"#$!

%"!

• !%"!&

'(#!"("#) !%"! '%!*(!) +,- ,- . /0! $%"!&% !( $1"

Transportable source - Sr

/01. /01. /01. Frequency generation system

• Small footprint (110 x 90 cm)
• Low power consumption
• High-power diode laser system for

1st stage cooling

• Move from Florence to Braunschweig

in January 2010

Atomic clocks for space - ACES

• Projected launch: ~ 2014
• PHARAO: cold atom microwave clock
• instability 1.10-13 at 1 s, 4.10-16 at 50 000 s
• accuracy ~ 1.10-16
• technology demonstrator
• world-wide time dissemination and comparisons
• test of special and general relativity

Future applications of transportable

• ptical clocks: Einstein Gravity Explorer
• Proposal within Cosmic Vision
• Ultrahigh stability optical clock (Ion and/or neutral atom)
• Primary objective: Fundamental tests of general relativity
• Projected resources: 200 W, 155 l, 125 kg (clock + frequency comb only)

Status and Perspectives

%7*+,*- $89 *9$ 5&

• 0.:

#,#$$"2( (+*+ 7*+,*;$*9 <'8(++=*99*(9