1. QUPLAS
Marco G. Giammarchi
Istituto Nazionale Fisica Nucleare – Milano
On behalf of the QUPLAS group (Collaboration)
Q U P L A S
QUantum Interferometry, decoherence and gravitational studies with Positrons and LASers
Outline of talk:
Home of the Experiment:
L-NESS Laboratory of the Politecnico di Milano - Polo territoriale di Como.
QUPLAS Concept
QUPLAS Physics
QUPLAS Proposal and Financial Issues
10/10/2017
Quplas CSN2 - July 2015

2. The QUPLAS Collaboration
Università degli Studi di Milano and Infn Milano
S. Castelli, S. Cialdi, M. Giammarchi*, M. Longhi, G. Maero, S. Olivares,
M. Paris, M. Potenza, M. Romè, S. Sala, S. Siccardi, D. Trezzi
Politecnico di Milano (Polo territoriale di Como)
S. Aghion, M. Bollani (IFN del CNR), G. Consolati, R. Ferragut, M. Leone
Albert Einstein Center – Laboratory for HEP – University of Bern
A. Ariga, T. Ariga, A. Ereditato, C. Pistillo, P. Scampoli
Dep.t of Chemistry, University of Bath
K. Edler
R. Greaves (Los Angeles, formerly at First Point Scientific)
10/10/2017
Quplas CSN2 - July 2015

3. Ps : the truly elementary atom
A pure QED system where spin-orbit and hyperfine effects are of the same order
Our systems of interest :
Electron (an elementary fermion)
Positron (the antifermion)
Positroniuim (Ps, a particle/antiparticle symmetric system)
10/10/2017
Quplas CSN2 - July 2015

4. Positrons and Positronium (Ps)e+
A conversion target
ortho-Ps is short lived
But its lifetime can be increased by exciting it on a Rydberg (high-n) state
10/10/2017
Quplas CSN2 - July 2015

5. Introduction to the concept of Quantum Interferometry of Ps
The typical structure of a Quantum Mechanical Experiment
Preparation :
e+ beam
Ps beam
Target
Laser (excitation)
First grating
Detection :
Recording interference pattern
Projection on measurement eigenstates
Preparation
Detection
Interaction
Propagation
Interference
Non – ideality :
Incoherence
Non – ideality :
Decoherence
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Quplas CSN2 - July 2015

6. New Fundamental Physics
QUPLAS concept
Synergy of technologies developed in different areas as well as new technologies:
Positrons and positronium techniques (Como)
Positron beams, moderation and plasmas (Como, Milano)
Special converters for Ps production in transmission mode (Bath, Milano)
Laser excitation for positronium (Milano)
Emulsion techniques for precise measurements (Bern)
New Fundamental Physics
10/10/2017
Quplas CSN2 - July 2015

7. Quantum Interferometry (mostly) in the Talbot regime
QUPLAS Physics
Quantum Interferometry (mostly) in the Talbot regime
S. Sala, F. Castelli, M. Giammarchi, S. Siccardi and S. Olivares – Matter-wave interferometry: towards antimatter interferometers. Submitted to J. of Phys. B, Atomic, Molecular and Optical Physics, arxiv: [quant-ph].
Positrons and electrons quantum waves interference (QUPLAS-0)
Positronium quantum interference (QUPLAS-I)
Positronium quantum dynamics and decoherence studies
Positronium gravitational studies : free fall ! (QUPLAS-II)
10/10/2017
Quplas CSN2 - July 2015

8. The facility: the Como continuous positron beam
The VEPAS Laboratory at the L-Ness Politecnico di Milano at Como Center.
(R. Ferragut)
Slow positron beam. 1. Radioactive source; 2. Electrostatic optics; 3. Sample chamber; 4. HpGe detectors; 5. Cryostat; 6. High voltage protection cage; 7. Power suppliers; 8. Detector electronics.
Original intensity of the source: 50 mCi
Current intensity: ~ 13 mCi
Tungsten moderator  reduces the energy from the beta spectrum down to a few eV
Electrostatic transport  positron beam
10/10/2017
Quplas CSN2 - July 2015

9. The general structure
A continuous positron beam (better than a bunched beam for interferometry!)
Transmission targets (technical focus of development, Bath and Milano)
Possible electrostatic system to focus the Ps in the forward direction
Laser system to excite Ps in a velocity selective way !
Micrometrix SiNx gratings (made at LNESS)
Nuclear emulsions provided by the Bern group.
10/10/2017
Quplas CSN2 - July 2015

10. Talbot carpets 2 1 Fraunhofer regime setting in when L>>LT
The characteristic pattern of the Talbot effect can be used to make sure the observed effect is the Talbot effect for the specified wavelength
Units
Talbot length
Fringes visibility for the given wavelength 2 1
Fraunhofer regime setting in when L>>LT
«Ballistic» moiré regime
10/10/2017
Quplas CSN2 - July 2015

11. The QUPLAS Laser system for velocity-selective excitation of a continuous Ps beam
Excitation of Rydberg states :
1 nm 2n ~ 732 nm
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Quplas CSN2 - July 2015

12. The QUPLAS Laser system for velocity-selective excitation of a continuous Ps beam
10/10/2017
Quplas CSN2 - July 2015

13. Talbot Optics in the Laboratory
Classical Optics experiments to guideline the particle experiments µm
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Quplas CSN2 - July 2015

14. The de Broglie wavelength
QUPLAS - 0
Positron beam energy: from a few keV up to 20 keV
Reference value: 10 keV
Intensity: ~ 4 x 104 e+/s
The de Broglie wavelength
Given a grating with
One can choose b = c = 33 cm
To have a 2 µm periodicity pattern on C
Setup preparation
Exposure to the e+ beam
Integration on the emulsion detector C
The Talbot length
10/10/2017
Quplas CSN2 - July 2015

15. An experimental activity that has already started with low-cost tests:
QUPLAS - 0
An experimental activity that has already started with low-cost tests:
Emulsion exposures to the VEPAS e+ beam
3 exposures made at energies ranging from 6 keV to 20 keV
Positron source  Electron source in preparation in the same apparatus
(electron emitting tips) :
Preliminary result: e+ visible down to 10 keV in emulsions!
Quantum Interferometry with 10 keV positrons
Quantum Interferometry with 10 keV electrons (in the very same apparatus)
a teeny-tiny CPT test (fermion/antifermion comparison never done before) to start with
10/10/2017
Quplas CSN2 - July 2015

16. Stripes prototype made by Electron Beam Lithography
QUPLAS - 0
SiN
thickness 200/500 nm
5 mm x 5 mm
Micrometric (and nanometric)
gratings being developed on SiN substrates
Stripes prototype made
by Electron Beam
Lithography 
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Quplas CSN2 - July 2015

17. Excitation on Rydberg state is necessary. Laser excitation required.
QUPLAS - I
Positronium Quantum Interferometry concept
Positron Interferometry
Electron Interferometry
Positronium Interferometry
An elementary fermion
The relevant antifermion
The bound fermion-antifermion system
(also, the simplest atom)
Problems to face :
Positronium is a neutral atom
Positronium has a very short lifetime
Detection of the interference pattern is not going to be easy. Ionization required.
Excitation on Rydberg state is necessary. Laser excitation required.
QUPLAS – I physics program:
Quantum Decoherence with an unusual system
Wave function interpretation
Optical gratings and laser interaction and cooling
10/10/2017
Quplas CSN2 - July 2015

18. Samples. Micrometre membranes
Synthesis route to the growth of free-standing surfactant-template films of silica (Chemistry Department, University of Bath, Claverton Down, Bath) [1]
Calcination (400oC)
[1] K.J. Edler* and B. Yang, Chem. Soc. Rev.,
, 3765
10/10/2017
Quplas CSN2 - July 2015

19. QUPLAS - II Positronium Gravity : why?
Answer : to test the Weak Equivalence Principle (test of General Relativity)
Universality of Free Fall
Matter
Weak Equivalence Principle tested on many different systems
Torsion Balance Measurement
10-13 level reached
Antimatter
g not measured
Antihydrogen program at CERN (e. g. The AEgIS experiment)
Aiming at ~ % accuracy
Positronium
Matter/Antimatter system ?
10/10/2017
Quplas CSN2 - July 2015

20. Measuring gravity Methods to measure the Interference Pattern Shift
Quantum Talbot Interferometry (pitch of ~ 100 microns) S. Sala et al., submitted to J. of Phys. B, Atomic, Molecular and Optical Physics, arxiv: [quant-ph].
Moiré classical deflectometry (pitch of ~ mm) S. Aghion et al., Nature Comm doi: /ncomms5538.
10/10/2017
Quplas CSN2 - July 2015

21. The third method to measure gravity («space – gamma»)
3. Simple method of tracing a given velocity selected by the laser (highly efficient on NaI)
Three different methods to measure g
Talbot interferometry
Moiré deflectometry
Space-gamma
Different picthes for the gratings but similar systematics and blank measurements
Entirely different systematics
10/10/2017
Quplas CSN2 - July 2015

22. Gravity measurement count rate
Count rate for a typical gravity experiment
50 mCi source with a RGM moderator (0.4% efficiency)  7 x 106 e+/s
e+  Ps conversion (10%) and reemission (30%) by converters  2 x 105 /s
Ps solid angle of emission and interferometer geometry (0.1%)  200/s
Ps excitation efficiency is high but the spectral selection will introduce 10%  20/s
Transparency of the gratings 25%  5/s
Sensitivity to g for Ps (only Talbot, interferometric methods)
Given 0.5 dots/s on the emulsion, one has, for a very realistic 50% contrast, d3 = 476 μm, Δx = 4 μm :
2% in a WEEK
1% in a MONTH
<0.1% in a YEAR
10/10/2017
Quplas CSN2 - July 2015

23. QUPLAS – 0 activity already taking place
QUPLAS Proposal and Financial issues
QUPLAS – 0 activity already taking place
QUPLAS-0 activity is already supported by :
Politecnico di Milano (use of the VEPAS Laboratory)
University of Bern (operation, development, use of the emulsion detectors)
University of Bath (transmission targets development)
The full capital cost (all QUPLAS phases) of the experiment is of about :
150 kEur (moderator)
250 kEur (laser system)
< 200 kEur (gratings,beamline,detectors)
Request for an ERC Advanced Grant presented (PI: M. Giammarchi)
The expense profile in Infn forms is intended to be a worst case scenario
Possible FET for the laser part (S. Cialdi)
10/10/2017
Quplas CSN2 - July 2015

24. The Infn proposal (in preparation, preliminary)
Infn Milano :
Stefano Aghion (AsRic Politecnico) 50%
Monica Bollani (IFN Cnr Politecnico) 20%
Fabrizio Castelli (RU Dipartimento) 50%
Simone Cialdi (RU Dipartimento) 50%
Giovanni Consolati (PA Politecnico) 50%
Rafael Ferragut (PA Politecnico) 50%
Marco Giammarchi (PR Infn) 50%
Mariangela Longhi (RU Dip. Chimica) 20%
Giancarlo Maero (RUTD Dipartimento) 15%
Stefano Olivares (RU Dipartimento) 50%
Matteo Paris (PA Dipartimento) 50%
Marco Potenza (RU Dipartimento) 40%
Massimiliano Romè (RU Diparitmento) 15%
Davide Trezzi (AsRic UNIMI) 20%
TOTAL %
We require Infn approval and will discuss a flexible financial profile
2016 request will focus on the support of QUPLAS-0 (and some laser development)
(Major investments will be proposed after QUPLAS-0 will demonstrate the technology)
2016
Costruzione Apparati 18 k Eur (interferometers, laser optics)
Consumi k Eur (gratings, targets)
Trasferte k Eur
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Quplas CSN2 - July 2015

25. Backup slides
10/10/2017
Quplas CSN2 - July 2015

26. The QUPLAS Test of the WEP
WEP (Weak Equivalence Principle) : the gravitational acceleration of any object is independent from the object composition.
Tested with Matter with a precision of ~10-13
Antimatter has a profound theoretical meaning (Special Relativity and Quantum Mechanics)
WEP has never been tested with precision with Antimatter
WEP is a Classical Symmetry
Theories of Quantum Gravity include non-tensor terms. These gravi-vector and gravi-scalar components can have different signs for matter and antimatter.
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Quplas CSN2 - July 2015

27. The QUPLAS Lser System
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Quplas CSN2 - July 2015