1 / 10

HYPER

HYPER. Hyper-Precision Cold Atom Interferometry in Space Limits on Quantum Gravity. ROBERT BINGHAM. Rutherford Appleton Laboratory,Chilton, Didcot, Oxon. OX11 0QX. HYPER - Atom interferometers and Quantum Gravity.

amy
Télécharger la présentation

HYPER

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. HYPER Hyper-Precision Cold Atom Interferometry in Space Limits on Quantum Gravity ROBERT BINGHAM Rutherford Appleton Laboratory,Chilton, Didcot, Oxon. OX11 0QX

  2. HYPER - Atom interferometers and Quantum Gravity • Grand unification theory (GUT) predict that the four forces of nature unify close to the planck scale. • Spacetime is smooth on the normal scales but granulated due to quantum gravity on the Planck scale  Quantum Foam • Planck time planck  G c   s • Planck length cplanck  G c2   35 m • Planck mass Mplanck  c/G  10-8kg • Planck energy  1019 GeV Planck mass

  3. HYPER - Atom interferometers and Quantum Gravity • Quantum Foam • Spacetime at the Planck scale is topologically nontrivial, manifesting a granulated structure  Quantum Foam • Quantum decoherence puts limits on spacetime fluctuations at the Planck scale. • Semi-classical and Superstring theory support the idea of loss of quantum coherence.

  4. HYPER - Atom Interferometers and Quantum Gravity • How can an atom interferometer measure physics on the Planck scale? • Einstein’s (1905) Brownian motion work of inferred properties of atoms by • observing stochastic motion of macrostructure’s • Space time fluctuations on the Planck scale produce stochastic phase shifts. •  • Possible to measure space-time • fluctuation Amplitude Aplanck Aplanck Diffusion of the wave function. Produces decoherence in an atom interferometer (Powers & Percival 1999, Ellis 1990))

  5. HYPER - Atom Interferometers and Quantum Gravity • Stochastic Process • Quantum gravity fluctuations  stochastic phase shifts • A stochastic process like Brownian • motion is a diffusion process  • Regular phase due to smooth spacetime • shift is . • Space time fluctuations  regular • phase  multiplied by to/. • Results in fluctuating phase • to • [Percival 1997]

  6. HYPER - Atom Interferometers and Quantum Gravity • Physics of Decoherence • Difficult to avoid interaction with environment. • Natural Vibrations of the system. • Collisions with ambient particles. • Interaction with its own components. • Black body radiation. • Spacetime time quantum fluctuations.

  7. Atom Interferometer Classical gravitational fields  regular phase change  Along a path with an interval of proper time,   =  Mc2/ quantum angular frequency, mass M of the atom. (Atom mass number   1. s) • Spacetime fluctuations •  Stochastic phase change () •   to/   ( planck 

  8. HYPER - Atom Interferometers and Quantum Gravity • Granulation of space-time - Universe no longer four dimensional, • higher number of dimensions are required. • e.g. Superstring theory - 10 dimensions • Length scale below which granulation is important • This is an effective cut-off for Quantum gravity theories determined by the amplitude of zero point gravitational fluctuations • where is the cut-off frequency, and • From theoretical considerations  is in range 102 - 106 • Current experiments using atom Interferometers by Peters et al., 1997 set a lower bound of  > 18. • Improvements on experimental sensitivity can raise this value.

  9. Quantum Limits on Atom Interferometers • In matter interferometers it is difficult to avoid interactions with the environment and these also suppress the interference. • The decoherence may be caused by interaction with blackbody radiation, collisions, restraint by a tie down system or even interaction with its own components/atoms. • Position uncertainty limit is • The challenge is to detect the spacetime fluctuations unambiguously. • HYPER will put upper limits to the measurement of decoherence providing tests for the various theories.

  10. HYPER - Atom Interferometers and Quantum Gravity • Conclusions • Theories of Quantum gravity support the idea of loss of coherence in matter interferometers. • In matter interferometers it is difficult to avoid interactionswith the environment. • The challenge is to detect the spacetime fluctuations unambiguously • HYPERwill put upper limits to the measurement of decoherence providing tests for the various theories of quantum gravity.

More Related