Virtual state (physics)

The term virtual state is commonly used to refer to two different types of states in physical systems. It may refer to a very short-lived, unobservable quantum state or a real, but unstable, state. Early definitions of the term (for example, see [1]) appear to distinguish the virtual state from the "virtual quantum."

Contents

Quantum State

In many quantum processes a virtual state is an intermediate state, sometimes described as "imaginary"[2] in a multi-step process that mediates otherwise forbidden transitions. Since virtual states are not eigenfunctions of anything [3], normal parameters such as occupation, energy and lifetime need to be qualified. No measurement of a system will show one to be occupied,[4] but they still have lifetimes derived from uncertainty relations[5][6]. While each virtual state has an associated energy, no direct measurement of its energy is possible[7] but various aproaches have been used to make some measurements( for example see [8] and related work [9][10] on virtual state spectroscopy) or extract other parameters using measurement techniques that depend upon the virtual state's lifetime[11]. The concept is quite general and can be used to predict and describe experimental results in many areas including Raman spectroscopy[12], non-linear optics generally[13], various types of photochemistry [14], and/or nuclear processes [15]. The term is often invoked in speculative treatments of such controversial topics as cold fusion, zero-point energy extraction[ citations to follow] , time-travel, anti-gravity, and consciousness[16][17][18].

Unstable State

The term virtual state can also be used to refer to bound or transient states which can decay into free states or relax at some finite rate[19]. This state may be the metastable state of a certain class of Feshbach resonance , "A special case of a Feshbach-type resonance occurs when the energy level lies near the very top of the potential well. Such a state is called 'virtual'"[20] and may be further contrasted to a shape resonance depending on the angular momentum.[21]. Because of their transient existence, they can require special techniques for analysis and measurement, for example[22][23][24][25].

See also

References

  1. ^ A glossary of terms in nuclear science and technology: a series of nine sections By National Research Council (U.S.). Conference on Glossary of Terms in Nuclear S American Society of Mechanical Engineers, 1953 page 61
  2. ^ Science, Volume 227 American Association for the Advancement of Science, HighWire Press, JSTOR 1985 page 736
  3. ^ Barry R. Masters, Peter T. C. So Handbook of Biomedical Nonlinear Optical Microscopy Oxford University Press US, 2008 ISBN 0195162609, 9780195162608 page 10
  4. ^ David Alan Wardle Raman Scattering in Optical Fibres, thesis Doctor of Philosophy in Physics The University of Auckland , January 1999 page 22
  5. ^ Nonlinear Optics and Laser Spectroscopy By S C Abbi, S. A. Ahmad page 139 ISBN 8173193541, 9788173193545
  6. ^ Non-linear optical properties of matter: from molecules to condensed phases By Manthos G. Papadopoulos, Andrzej Jerzy Sadlej, Jerzy Leszczynski page 3 Springer, 2006 ISBN 1402048491, 9781402048494
  7. ^ Dzevad Belkic Principles of quantum scattering theory page 70 CRC Press, 2004 ISBN 0-7503-0496-0,9780750304962
  8. ^ Bahaa E. A. Saleh, Bradley M. Jost, Hong-Bing Fei, and Malvin C. Teich Entangled-Photon Virtual-State Spectroscopy VOLUME 80, NUMBER 16 PHY S I CAL REV I EW LETTERS 20 APRIL 1998 S0031-9007(98)05928-6 page 3483
  9. ^ Jun KojimaCorresponding Author Contact Information, a, E-mail The Corresponding Author and Quang-Viet Nguyen Entangled biphoton virtual-state spectroscopy of the A2Σ+–X2Π system of OH Chemical Physics Letters Volume 396, Issues 4-6, 1 October 2004, Pages 323-328
  10. ^ Dong-Ik Lee and Theodore Goodson III Quantum spectroscopy of an organic material utilizing entangled and correlated photon pairs Proc. SPIE, Vol. 6653, 66530V (2007); doi:10.1117/12.745492
  11. ^ F. Boitier, A. Godard, E. Rosencher & C. Fabre Measuring photon bunching at ultrashort timescale by two-photon absorption in semiconductors Nature Physics 5, 267 - 270 (2009) Published online: 15 March 2009 doi:10.1038/nphys1218
  12. ^ Peter R. Griffiths, James A. De Haseth Fourier Transform Infrared Spectrometry, Volume 83 second ed, Wiley-Interscience, 2007 ISBN 0470106298, 9780470106297 page 16
  13. ^ S C Abbi, S. A. Ahmad Nonlinear Optics and Laser Spectroscopy, Alpha Science Int' Ltd., 2001 ISBN 8173193541, 9788173193545 page 139
  14. ^ Douglas C. Neckers, William S. Jenks, Thomas Wolff Advances in Photochemistry, Volume 29 John Wiley and Sons, 2006 ISBN 0-471-68240-3, 9780471682400 page 116
  15. ^ Proceedings of the NATIONAL ACADEMY OF SCIENCES Volume 67 Number 4 * April 15, 1967 VIRTUAL COULOMB EXCITATION IN NUCLEON TRANSFER* BY G. BREIT
  16. ^ Lothar Schäfer TI: QUANTUM REALITY, THE EMERGENCE OF COMPLEX ORDER FROM VIRTUAL STATES, AND THE IMPORTANCE OF CONSCIOUSNESS IN THE UNIVERSE SO: Zygon(r) VL: 41 NO: 3 PG: 505-532 YR: 2006 ON: 1467-9744 PN: 0591-2385 DOI: 10.1111/j.1467-9744.2005.00755.x US: http://dx.doi.org/10.1111/j.1467-9744.2005.00755.x
  17. ^ Lothar Schäfer A RESPONSE TO ERVIN LASZLO: QUANTUM AND CONSCIOUSNESS Zygon(r) VL: 41 NO: 3 PG: 573-582 YR: 2006 ON: 1467-9744 PN: 0591-2385 10.1111/j.1467-9744.2005.00759.x http://dx.doi.org/10.1111/j.1467-9744.2005.00759.x
  18. ^ Antonella Vannini , Quantum Models of Consciousness , Quantum Biosystems 2008, 2, 165-184
  19. ^ On the Dynamics of Single-Electron Tunneling in Semiconductor Quantum Dots under Microwave Radiation Dissertation Physics Department of Ludwig-Maximilians-Universitat Munchen by Hua Qin from Wujin, China 30th July 2001, Munchen
  20. ^ Schulz George Resonances in Electron Impact on Atoms and Diatomic Molecules Reviews of Modern Physics vol 45 no 3 pp378-486 July 1973
  21. ^ Donald C. Lorents, Walter Ernst Meyerhof, James R. Peterson Electronic and atomic collisions: invited papers of the XIV International Conference on the Physics of Electronic and Atomic Collisions, Palo Alto, California, 24-30 July, 1985 North-Holland, 1986 ISBN 0444869980, 9780444869982 page 800
  22. ^ D. Field1 *, N. C. Jones1, S. L. Lunt1, and J.-P. Ziesel2 Experimental evidence for a virtual state in a cold collision: Electrons and carbon dioxide Phys. Rev. A 64, 022708 (2001) 10.1103/PhysRevA.64.022708
  23. ^ B. A. Girard and M. G. Fuda Virtual state of the three nucleon system Phys. Rev. C 19, 579 - 582 (1979) 10.1103/PhysRevC.19.579
  24. ^ Tamio Nishimura * and Franco A. Gianturco Virtual-State Formation in Positron Scattering from Vibrating Molecules: A Gateway to Annihilation Enhancement Phys. Rev. Lett. Volume 90Issue 18 Phys. Rev. Lett. 90, 183201 (2003) 10.1103/PhysRevLett.90.183201
  25. ^ Kurokawa, Chie; Masui, Hiroshi; Myo, Takayuki; Kato, Kiyoshi Study of the virtual state in νc10Li with the Jost function method American Physical Society, First Joint Meeting of the Nuclear Physicists of the American and Japanese Physical Societies October 17 - 20, 2001 Maui, Hawaii Meeting ID: HAW01, abstract #DE.004