INSTITUT MAX VON LAUE - PAUL LANGEVINV.V. Nesvizhevsky10.03.1610.03.16

Gravitational Quantum Spectroscopy(GRANIT and GBAR collaborations)

Plan of presentation

- References - Introduction- Motivations- Recent improvements- Conclusions and prospects

Gravitationalquantumspectroscopywith neutrons

Gravitationalquantumspectroscopywithantihydrogenatoms

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

References

Observation of gravitational states of neutrons: ([V.V. N., H.G.Boerner, A.K. Petukhov, H. Abele, S. Baessler, F.J. Ruess, T.Stoferle, A. Westphal, A.M. Gagarski, G.A. Petrov, and A.V.Strelkov, Quantum states of neutrons in the Earth’s gravitationalfield, Nature 415:297, 2002];

Observation of centrifugal states of neutrons: [V.V. N., A.Yu.Voronin, R. Cubitt, and K.V. Protasov, Neutron whispering gallery,Nature Physics 6:114, 2010];

Proposal: [A.Yu. Voronin, V.V. N., P. Froelich, Gravitationalquantum states of antihydrogen, Phys. Rev. A 83:032903, 2011];

GRANIT proceedings: [GRANIT-2014, Gravitational QuantumSpectroscopy, Adv. High En. Phys. 467409:2, 2014]; [GRANIT-2010,Compt. Rend. Phys. 12:703, 2011];

GBAR: talks at LEAP-2016.

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Series of GRANIT workshops every 4th (Olympic) year

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Gravitational Quantum Spectroscopy

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Gravitational Quantum Spectroscopy

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Quantum states, quantum fall and equivalence principle

Quantumstates

Quantumfall

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Equivalence: gravity and acceleration

Gravitational and whispering-gallery quantum states of neutrons

Essential features:- The mirror is a uniform

potential barrier, with nointernal structure,

- The particles are reflectedfrom the mirror elastically,

- Ultracold neutrons (UCNs)are unique particles formeasuring such quantumstates.

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Gravitational and whispering-gallery quantum states of neutrons

Essential features:- The mirror is a uniform

potential barrier, with nointernal structure.

- The particles are reflectedfrom the mirror elastically.

- Ultracold neutrons (UCNs)are unique particles formeasuring such quantumstates.

My fault. UCNs are not unique particles in this sense. NearlyALL particles with sufficiently large wavelength and smallenergy are reflected elastically from surfaces.

Choice of a particle

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Quantum reflection

Problem: attractive van derWaals/Casimir-Polder potential.

Solution: Quantum reflection is thelimit of lowest energies (gravitationalquantum states!!!) provides nearly totalreflection of a particle from a mirror.

The quantum reflection of atoms hasbeen demonstrated.

The importance of quantum reflectionof anti-atoms in the low-energy limit(gravitational quantum states) wasnoticed by Alexei Voronin.

G. Dufour et al,Quantum reflectionof antihydrogen fromthe Casimir potentialabove matter slabs,Phys. Rev. A 87, 2013

Family of curves

INSTITUT MAX VON LAUE - PAUL LANGEVIN

10μm

30μm

20μm

40μm

Height above mirror

An illustration for quantum motion of a particle above a mirror in a gravitational field and that in an accelerated frame. The heights of the ball correspond to most probable heights of a neutron in 5th quantum state.

3

2

4

1

8

9

ng

mE n

n

10.03.16 V.V. Nesvizhevsky

Gravity / Acceleration

INSTITUT MAX VON LAUE - PAUL LANGEVIN

An “artistic” illustration for quantum motion of a particle built of normal matter (left) and antimatter (right) in a gravitational field

?

Gravitational properties of antimatter have never been measured directly

? ?...

10.03.16 В.В. Несвижевский

Matter / Antimatter

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

“Let us consider another possibility, an atom held together bygravity alone. For example, we might have two neutrons in a boundstate. When we calculate the Bohr radius of such an atom, we findthat it would be 108 light years, and that the atomic binding energywould be 10−27 Rydberg. There is then little hope of ever observinggravitational effects on systems which are simple enough to becalculated in quantum mechanics.” Brian Hatfield in [R.P. Feynman,F.B. Morinigo, and W.G. Wagner (1995) Feynman Lectures onGravitation (Addison-Wesley, USA), p. 11]

Yesterday's sensation is today’s calibration and tomorrow’sbackground” [P.R. Feynman and V.L. Telegdi]

Motivations

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Gravitational quantum states of anti-hydrogen atoms as a toolfor precision direct measurements of gravitational properties ofantimatter (GBAR). Advantages: precision spectroscopic methods,long observation time, localization in space and in energy -> smallersystematic effects and lower costs

Motivations

Characteristicquantum time equalsΔτ~ℏ/ΔE~0.5ms

Characteristicprecision equalsΔg/g~Δτ/T/100~10-4,where T is the time ofstorage of antiatomsin gravitational states

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

- For specially “adjusted” van der Waals/Casimir potentials,storage times of gravitational quantum states can be significantlyincreased;

- Careful analysis of systematic effects and better statisticscan allow further significant improvement of accuracy

Motivations

Characteristicquantum time equalsΔτ~ℏ/ΔE~0.5ms

Precision can probablyapproach (?)Δg/g~Δτ/T/103~10-6,where T is the time ofstorage of antiatomsin gravitational states

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Gravitational quantum states of hydrogen atoms as a tool forprototyping the GBAR experiment with antihydrogen atoms (N.Kolachevsky, A.Yu. Voronin, V.V. N. et al) and also as an independentmethod for constraining short-range fundamental forces.Advantages: huge statistics, existing techniques

The prototyping isbased on symmetryof matter andantimatter relativeto electromagneticinteractions

Motivations

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Classical fall

Gravitational quantum experiment in steps

Quantum fall

Quantum states

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Gravitational quantum states of positronium as a tool tomeasure gravitational fall of positronium with minimum systematicaleffects [P. Crivelli et al, Can we observe the gravitational quantumstates of positronium? Advances in High Energy Physics (2015) inpress]. Advantages: localization in space allows reduction ofsystematic effects

For completeness: various other realizations

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Whispering-gallery quantum states of cold neutrons, atoms,antiatos as a sensitive and universal method to explore surfaces(including the standard surface potentials and fundamental short-range forces). Examples: in-situ monitoring of the growth of thinfilms, surface diffusion etc.

Advantages: long observation time,thus huge increase in sensitivity; apossibility to use standardreflectometers for cold neutronsavailable in all neutron centers inthe world.

For completeness: various other realizations

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Other options being discussed but not yet developed andformalized:- Astrophysical realizations of quantum bouncing,- Nanoparticles and nanodroplets in the vicinity of surfaces,- Polarized 𝐻𝑒3.

For completeness: various other realizations

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Fundamental short-range forces and neutrons

Short-range forces

Phenomenologically:

- Spin-independent,- Spin-dependent.

Origin:

- Extra light bosons,- Extra spatial dimensions,- Dark matter (chameleons),- Axion-like particles etc

Neutrons

- Electric neutrality,

- Availability of high fluxes ofneutrons with wavelengthscomparable to the spatialscale of extra interactionsto probe,

- High probability of elasticinteraction with matter.

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Fundamental short-range forces and neutrons

All measurements with neutrons related to the topic of my talk areperformed at the Institut Max von Laue – Paul Langevin (ILL),Grenoble, France. All measurements involve ILL scientists and alsoall measurements use ILL facilities.

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Short-range forces. State of the art.

I. Antoniadis, S. Baessler, M. Buchner, V.V. Fedorov, S. Hoedl, V.V. N., G. Pignol, K.V. Protasov, S. Reynaud, Yu. Sobolev, « Short-range fundamental forces », Compt. Rendu Acad. Sci . 12 (2011) 775.

Particle-particle

Particle-matter

Matter-matter

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

I. Antoniadis, S. Baessler, M. Buchner, V.V. Fedorov, S. Hoedl, V.V. N., G. Pignol, K.V. Protasov, S. Reynaud, Yu. Sobolev, « Short-range fundamental forces », Compt. Rendu Acad. Sci 12 (2011) 775.

Short-range forces. State of the art.

Particle-matter

Axion windowof distances

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Short-range forces. More recent improvements

Measurements using UCNs in theEDM apparatus at PSI (Villigen,Switzerland) [S. Afach et al,Phys. Let. B (2015) in press].Red line (H) shows the newconstrain derived from thisexperiment.Solid line (I) indicates anachievable constraint that couldbe obtained with a modifiedinstallation.

Slightly better (then H)constraint was recentlymeasured with polarized 𝐻𝑒3

(A.K. Petukhov, G. Pignol et al)

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Neutron gravitational states.- Several independent groups (Tokyo, QBounce, GRANIT);- Many new good results in the flow-through mode !! (Qbounce,

Tokyo);- Building a dedicated facility at ILL for experiments with

gravitational quantum states of neutrons in the long-storagemode (GRANIT);

- Neutron results for short-range forces are not yet competitiveto results of short-range gravity and Casimir experiments butthey are rapidly improving (remember that one should improveby 5-6 orders of magnitude; however, no major systematiceffects associated with neutrons have been identifies);

- Significant worldwide effort to increase available densities ofUCNs.

Short-range forces. More recent improvements

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Neutron gravitational states.- Several independent groups (Tokyo, QBounce, GRANIT);- Many new good results in the flow-through mode !! (Qbounce,

Tokyo);- Building a dedicated facility at ILL for experiments with

gravitational quantum states of neutrons in the long-storagemode (GRANIT);

- Neutron results for short-range forces are not yet competitiveto results of short-range gravity and Casimir experiments butthey are rapidly improving (remember that one should improveby 5-6 orders of magnitude; however, no major systematiceffects associated with neutrons have been identifies);

- Significant worldwide effort to increase available densities ofUCNs.

My fault. There are potentially significant systematic effects,particularly in the flow-through mode, but they could be suppressedby properly designing experiments and by making proper analysis ofsystematic effects

Short-range forces. More recent improvements

INSTITUT MAX VON LAUE - PAUL LANGEVINV.V. Nesvizhevsky

Flow-through mode; limitedobservation time

Storage mode: ultimate observation time and energy resolution

Probabilityof transition

Perturbation frequency, Hz

ijji wEE

Hz25621

eVE 18

min 10

6

12

min 10 EE

E

Transitions could be excited, for instance:

- By periodically varying magnetic field gradient;

-By periodically varying local gravitational field;

-By oscillating mechanically the mirror.

V.V. Nesvizhevsky, and K.V Protasov, “Quantum states of neutrons in the Earth’s gravitational field: state of the art, applications, perspectives” in Edited book on

Trends in Quantum Gravity Research (D.C. Moore, New York, USA, NOVA; pp. 65-107)

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Transitions between gravitational quantum states

INSTITUT MAX VON LAUE - PAUL LANGEVINV.V. Nesvizhevsky

Main Mirror

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Gravitational quantum states in a storage mode

INSTITUT MAX VON LAUE - PAUL LANGEVINV.V. Nesvizhevsky

Main Mirror

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Gravitational quantum states in a storage mode

Successful production of UCNs in ahelium UCN source and extraction ofUCNs to the GRANIT spectrometer

INSTITUT MAX VON LAUE - PAUL LANGEVINV.V. Nesvizhevsky

Main Mirror

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Commissioning of the GRANIT spectrometer

- UCN fluxes from thesource are at the level ofworld best, and thussufficient for startingphysical measurementswith the spectrometer;

- UCN fluxes still have tobe improved for achievingthe ultimate precision;

- Commissioning of thespectrometer in theflow-through mode isnearly completed, realmeasurements will start17 May (restart of theILL reactor).

INSTITUT MAX VON LAUE - PAUL LANGEVINV.V. Nesvizhevsky10.03.16

GRANIT first measurements

- The simplest configuration ofthe GRANIT spectrometer inthe flow-through mode is similarto the first observation ofgravitational quantum states;

- Neighbouring quantum stateshave never been clearlyresolved experimentally;

- This is needed for 1) measuringmuch more precisely theparameters of quantum states,2) for providing contrast inexperiments with resonancetransitions betweengravitational quantum states.

INSTITUT MAX VON LAUE - PAUL LANGEVINV.V. Nesvizhevsky

Main Mirror

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First result are promising! 1) theabsorber is more efficient by anorder of magnitude, 2) UCN fluxis sufficient, 3) backgrounds areacceptable.

GRANIT first measurements

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Better precision and reliability for experiments with neutronwhispering gallery; record sensitivity; good chances for majorimprovements

Short-range forces. More recent improvements

INSTITUT MAX VON LAUE - PAUL LANGEVINV.V. Nesvizhevsky10.03.16

Theory

Experiment

Experiment

Theory

Neutrons tunnelingthrough the mirror

Neutrons passing tothe exit of the mirror

Short-range forces. More recent improvements

INSTITUT MAX VON LAUE - PAUL LANGEVINV.V. Nesvizhevsky

1

r

j

1

2

3

V

R3

5

4

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Better precisionand reliability forexperiments withneutron whisperinggallery; recordsensitivity; goodchances for majorimprovements

Short-range forces. More recent improvements

INSTITUT MAX VON LAUE - PAUL LANGEVIN10.03.1610.03.16 V.V. Nesvizhevsky

Conclusions

- The method of quantum bouncing is rapidly gaining ground,attention and support – good sign! It means that the method ispowerful, and “easy” for implementation;

- Neutron, and neutron-related, constraints for fundamentalshort-range forces are steadily improving in a very broad rangeof characteristic distances, due to efforts of different groupsusing different methods;

- Quantum bouncing of antihydrogen atoms promises the precisionof 10-4-10-6 for Δg/g; can be implemented in GBAR;

- All these activities are efficient in terms of results/resources;

- These tendencies will stay for the observable future.