Ultrafast preparation and strong-field ionization of an atomic Bell-like state

Molecules are many body systems with a substantial amount of entanglement between their electrons. Is there a way to break the molecular bond of a diatomic molecule and obtain two atoms in their ground state which are still entangled and form a Bell-like state? We present a scheme that allows for the preparation of such entangled atomic states from single oxygen molecules on femtosecond time scales. The two neutral oxygen atoms are entangled in the magnetic quantum number of their valence electrons. In a time-delayed probe step, we employ non-adiabatic tunnel ionization, which is a magnetic quantum number-sensitive mechanism. We then investigate correlations by comparing single and double ionization probabilities of the Bell-like state. The experimental results agree with the predictions for an entangled state.Comment: 20 pages, 7 figures, 1 tabl

BBC2 and world cinema

© Edinburgh University Press. This article examines the origins of BBC2's reputation as a purveyor of films from around the world, exploring the significance and impact of the strand World Cinema (1965-74) and assessing the range and diversity of its offer. Foreign-language titles had been broadcast by the Corporation since before the Second World War, due partly to their ready availability at a time when Hollywood films were 'off limits', given the hostility of American (and British) film companies towards the new rival medium of television. During this early period, however, these continental films were not popular, undoubtedly due to the fact that subtitles were very difficult to read on small, low-definition television screens. BBC2, with its commitment to minority tastes and interests and its use of both the higher-definition 625-line UHF system and colour, was perfectly placed to revive and foster interest in world cinema. For those who urged broadcasters to adopt and maintain an enlightened film policy, World Cinema became exemplary, as a rare exception to the general rules in early television of editing for content or length, block buying (the practice of buying the rights to a mixed package of films in order to acquire certain gems) and haphazard scheduling. For a generation of cinephiles, World Cinema was a formative and educative experience. Particular attention is paid here to the first five years of World Cinema, which saw the strand give attention to a variety of 'New Waves' and relay experiences from behind the Iron Curtain and further afield

Sideband Modulation by Sub-Cycle Interference

We experimentally and theoretically show that the electron energy spectra strongly depend on the relative helicity in highly intense, circularly polarized two-color laser fields which is an unexpected finding. The employed counter-rotating two-color (CRTC) fields and the co-rotating two-color (CoRTC) fields are both a superposition of circularly polarized laser pulses at a central wavelength of 390 nm and 780 nm (intensitiy ratio $I_{390}/I_{780}\approx 250$). For the CRTC field, the measured electron energy spectrum is dominated by peaks that are spaced by 3.18 eV (corresponds to the photon energy of light at a wavelength of 390 nm). For the CoRTC field, we observe additional energy peaks (sidebands). Using our semi-classical, trajectory-based models, we conclude that the sideband intensity is modulated by a sub-cycle interference, which sensitively depends on the relative helicity in circularly polarized two-color fields.Comment: 7 pages, 4 figure