Degenerate Quantum Gases manipulation on AtomChips Francesco Saverio Cataliotti

Bose-Einstein condensates on a microchip Atom Interferometry Multipath Interferometry on an AtomChip Results and ConclusionsOutlook

Degenerate atoms TemperaturaTemperatura T < T C Bosoni T < T F EFEF Fermioni

Degenerate Atoms 1925: Einstein predicts “condensation” of bosons 80’s: Development of laser cooling 1985: Magnetic Trapping of ultracold atoms 1986: Optical trapping of Na 1987: Na Magneto-Optical Trap 60’s: Development of Lasers 1995: First 87 Rb Bose-Einstein Condensate 2001: First BEC of 87 Rb on an Atom Chip Huge playground for fundamental physics: - BEC with Li, Na, K, Cs, Fr… - Optical gratings, collective excitations… First applications: - Interferometry - Earth and Space sensors - Quantum Information

T  300 K   Route to BEC in dilute gases laser cooling evaporative cooling   T  10  K T  100 nK   2.6

cooling trapping Magneto Optical Trap (MOT)

temperature Evaporative cooling Forced evaporation in a magnetic trap (conservative potential) remove highest velocities thermalization through elastic collisions cooling

BEC on a chip Macroscopic trap Micro-trap I Current ~ 100 A Power ~ 1.5 kW double MOT system: Laser power ~ 500 mW Ultra High Vacuum ~ Torr = Hz Current < 1 A Power < 10 W single MOT system: Laser power ~ 100 mW High Vacuum ~ Torr Large BEC 10 6 atoms but production cycle > 1 min BEC 10 5 atoms and production cycle ~ 1 s = kHz

++ ++ -- -- ++ -- Laser Cooling close to a surface

Planar Geometry  gold microstrips on silicon substrates B wir (I wir = 3A) B bias = {0,3.3,1.2} Gauss z (  m) x (  m) |B| (Gauss) I wir = 3 A ; B bias = {0,3.3,1.2} GaussI wir = 1 A ; B bias = {0,3.3,1.2} Gauss BEC on a chip

BEC Generation Routine MOT in reflection loading 10^8 atoms MOT transfer close to the chip (~1mm) CMOT + Molasses 5 x 10^7 T ~ 10 μK Optical pumping Ancillary magnetic trap (big Z wire) 20 x 10^6 T ~ 12 μK Compression and transfer to the magnetic trap on chip (chip Z wire) 20 x 10^6 T ~ 50 μK (~200 μm) Evaporation (big U under the chip) BEC with 30x10^3 atoms, Tc=0.5 μK End of the cycle time [ms]action 23000

lens CCD camera atoms Imaging cold atoms

MOT ~ 10^8 atoms Molasses phase ~ 5 x 10^7 T ~ 15 uK First Magnetic Trap (big Z wire) ~ 20 x 10^6 T ~ 12 uK Magnetic Trap on Chip (chip Z wire) ~ 20 x 10^6 T ~ 50 uK BEC ~ 20 x 10^3 T < 0.5 uK Free fall of the BEC BEC on a chip

Bose-Einstein condensates on a microchip Atom Interferometry Multipath Interferometry on an AtomChip Results and ConclusionsOutlook

Atom Interferometer coupling mechanism BEC 1 BEC 2 BEC 1,2 BEC 1 BEC 2 separation for measurement Rabi pulse Stern-Gerlach experiment BEC – coherent form of matter, a wavepacket BEC 1,2 different spin states

BEC on a chip

Atomic Ramsey Interferometer - Theory - Solve SE for 1 atom for the non-interacting BEC 1 2 Δ=ω 0 -ω ωω0ω0 let them evolve for time T mix them up again start from mix two states Solve GPE for the BEC

Rabi Oscillations mf=1 mf=2 time Tp BEC mf=1 BEC mf=2 B Δ space Stern-Gerlach method - pulse Rabi frequency

Rabi Oscillation Rabi frequency ~ 50KHz π/ mf

Experimental Scheme: Ramsey Interferometer mf=2 mf=1 mf=2 B Δ time space π/2

Oscillation frequency = 1/RF = 1/650KHz = 1.5 μs Ramsey Interferometer

Bose-Einstein condensates on a microchip Atom Interferometry Multipath Interferometry on an AtomChip Results and ConclusionsOutlook

Parameters of the Interferometric Signal background Sensitivity: Resolution: D’Ariano & Paris, PRA (1996) amplitude 24 Working range: Weihs et al., Opt. Lett. (1996)

Multi-path Interferometer

Multi-Path interferometer  Funny enougn for N>3 the system can be aperiodic since frequencies are incommensurable Even more fun they are the solutions of a complex Fibonacci Polynomial

Multi-Path interferometer There does not exist a  /2 pulse. To obtain the best resolution from the interferometer one has to optimize pulse area

Multi-Path interferometer There does not exist a  /2 pulse. To obtain the best resolution from the interferometer one has to optimize pulse area

Multi-Path interferometer

Bose-Einstein condensates on a microchip Atom Interferometry Multipath Interferometry on an AtomChip Results and ConclusionsOutlook

Detection of a Light-Induced Phase Shift Polarisation σ-Polarisation σ+ Light-pulse detuning from F=2  F=3 was 6.8GHz. 32 What can you use it for?

We have demonstrated a compact time-domain multi-path interferometer on an atom chip Sensitivity can be controlled by an RF pulse acting as a controllable state splitter. Resolution superior to that of an ideal two-path interferometer. Simultaneous measurement of multiple signals at the output enables a range of advanced sensing applications in atomic physics and optics Integration of interferometer with a chip puts it into consideration for future portable cold-atom based measurement systems.Conclusions

Atom Chip Team Ivan Herrera Pietro Lombardi our typical signal Jovana Petrovic Those who really did it

Ivan Herrera Pietro Lombardi A typical BEC Jovana Petrovic Who did it?

Ramsey Oscillation ExperimentTheory

cooling trapping Magneto Optical Trap (MOT)