Double‐Twisted Spectroscopy with Delocalized Atoms

Abstract

Interaction of atoms with twisted light is the subject of intense experimental and theoretical investigation. In almost all studies, the atom is viewed as a localized probe of the twisted light field. However, as argued in this paper, conceptually novel effects will arise if light‐atom interaction is studied in the double‐twisted regime with delocalized atoms, that is, either via twisted light absorption by atom vortex beam, or via two‐twisted‐photon spectroscopy of atoms in a non‐vortex but delocalized state. Even for monochromatic twisted photons and for an infinitely narrow line, absorption will occur over a finite range of detuning. Inside this range, a rapidly varying absorption probability is predicted, revealing interference fringes induced by two distinct paths leading to the same final state. The number, location, height, and contrast of these fringes can give additional information on the excitation process which would not be accessible in usual spectroscopic settings. Visibility of the predicted effects will be enhanced at the future Gamma factory thanks to the large momenta of ions.

Generation of vortex particles via generalized measurements

“…Twisted light with orbital angular momentum (OAM) projection Lz = 0 [1] has found numerous applications in quantum optics and information, optomechanics, biology, astrophysics, and so forth [2][3][4][5][6][7][8]. Along with the diffraction techniques, such photons can be generated by charged particles in undulators [9][10][11][12][13][14][15], via non-linear Thomson or Compton scattering [15][16][17][18][19][20][21], during Cherenkov and transition radiation [22], via channeling in crystals [23,24], etc.…”

“…The possible experiments with vortex muons, hadrons, ions, etc. are being discussed [8,27,28,37,38,44,[47][48][49][50][51][52] (see the recent review [53]), whereas the non-relativistic twisted atoms and molecules have been generated only recently [54]. However, the available diffraction techniques [26,[30][31][32]55] are not applicable for relativistic energies, which severely limits the development of the matter waves physics.…”

Promises and challenges of high-energy vortex states collisions

“…This scheme can become an intriguing alternative to beam energy scans when studying narrow resonant structures in particle production. In anticipation of future development of high-energy vortex state generation, one could verify the atomic spectroscopy counterparts of these predictions, where close atomic excited states replace the resonances [123].…”

The role of post-selection in generating vortex particles of arbitrary mass, spin, and energy

“…Photons with a quantized projection of orbital angular momentum (OAM) onto a propagation axis were predicted in Ref. [1] and found numerous applications in quantum optics and quantum information, optomechanics, biology, astrophysics, and in other fields [2][3][4][5][6][7][8][9]. Along with the conventional diffraction techniques, such twisted states of light can be generated by charged particles during electromagnetic emission in helical undulators [10][11][12][13][14][15], via non-linear Thomson or Compton scattering [15][16][17][18][19] or -more generally -when the electron's classical trajectory is helical [20,21], during Cherenkov radiation and transition radiation in media with different characteristics [22,23], and so forth.…”