Yael Bartana, Ritual

This exhibition of moving image works by the Amsterdam-based, Isaeli-born artist Yael Bartana explores how social ritual and everyday activities promote national and cultural cohesion. The works selected by curator Helena Reckitt, in tandem with the artist, capture the friction between public and private activities and identities, and that highlight the military's pervasive presence, group behaviour amidst political uncertainty, and the conquest, settlement, and defense of contested land. The exhibition also also included works that focus on forms of critique and protest enacted by residents of this militarised and hyper-nationalist nation-state, revealing a far-from homogenous or consensual range of subjectivities and political affiliations at play. In the moving image works included, Bartana makes the everyday strange by editing, manipulating and slowing down footage in order to isolate moments of ambivalence, resistance or over-compensation that undercut simple national and cultural affiliations, that the artist hopes might “provoke honest responses and perhaps replace the predictable, controlled reactions encouraged by the state.” Her approach to the quotidian has been likened to Polish-Canadian writer Eva Hoffman’s notion of "amateur anthropology. “ Yet while Hoffman’s focus is on the immigrant, who notices details that those who were raised within a culture take for granted, Bartana occupies the position of a national, whose passionate interest in her country of birth has been sharpened by her choice to live outside Israel, in Amsterdam, since 2000. Kings of the Hill (2003) depicts men driving their trucks and SUVs in the coastal hills near Tel-Aviv, watched by friends and family members. Motoring up and around the sandy dunes, their vehicles often lose traction and slide backwards. As night falls it is hard to tell whether we are witnessing familiar displays of macho prowess or something more sinister. The men's motors rev in Sisyphean futility, and seem to reflect the seemingly intractable permanence of Israel’s military mentality, as the silhouettes of these anonymous male figures are framed against the sky. Low Relief II (2004) combines documentation of several peace protests featuring both Israeli and Palestinian demonstrators, their military escorts and the overhead blimp that records them. Bartana has digitally adapted her footage to give it a silver, flattened quality that evokes relief sculpture. The ongoing process of political demonstrations takes on a timeless quality, becoming, in Bartana’s words, “a moving monument to the everyday reality of how it feels to live in Israel.” The two-screen projection Wild Seeds (2006) with its Biblical echoes of seeds growing in the desert, shows a group of young Israelis playing a game they have created. Named "Evacuation of Gilad's Colony," the game evolved from the forced withdrawal of Jewish settlers from the Occupied Territories and the violent confrontation between soldiers and settlers at Gilad's Farms in 2002. The teens themselves are third-generation Zionists who oppose Israeli's occupation of the West Bank. Two of the players act as soldiers while the others attempt to resist them. Filmed in the incongruously beautiful mountains of Prat's Settlement, Judean hills, one screen presents footage of the group’s antics while the other translates their words and sounds into English text. Wild Seeds suggests the impact that political violence and its resulting instability have on people's psyches and behaviour, a theme that carries through much of Bartana's work. Moving between manic playfulness and black humour, the game becomes a contemporary chronicle of a recent event that re-enacts the trauma of forced exodus. Profile (2001) focuses on compulsory military service in Israel through close-ups of a female soldier at target practice. The soldier's apparent awkwardness and ambivalence evoke the tension between self-determination and the demands of the nation-state. As Bartana states, “That soldier becomes a symbol that reflects my own feelings and emotions about the situation. I try to keep the viewer as an outsider and observer, and hope that this separation will allow them to connect to their own emotions as well.” The exhibition was accompanied by a discussion, ‘Contemporary Art in/out of the Middle East,’ which responded to the issues raised by the exhibition, on 21 March. Moderated by Professor and Associate Chair at the Visual Studies Program at the University of Toronto, filmmaker and co-founder of V-Tape Lisa Steele, speakers were Vicky Moufawad-Paul, Executive Director of the Toronto Arab Film Festival and Exhibition Coordinator at A Space; bh Yael, a Toronto-based filmmaker, installation artist and Associate Professor and Chair in Integrated Media at OCAD; and Carol Zemel, Professor of Modern and Contemporary Art History at York University. The discussion focused on the tensions and contradictions of the modern Israel that Bartana pictures, and on the efficacy of the ambivalent stance expressed in her work

Optimal control theory for unitary transformations

The dynamics of a quantum system driven by an external field is well described by a unitary transformation generated by a time dependent Hamiltonian. The inverse problem of finding the field that generates a specific unitary transformation is the subject of study. The unitary transformation which can represent an algorithm in a quantum computation is imposed on a subset of quantum states embedded in a larger Hilbert space. Optimal control theory (OCT) is used to solve the inversion problem irrespective of the initial input state. A unified formalism, based on the Krotov method is developed leading to a new scheme. The schemes are compared for the inversion of a two-qubit Fourier transform using as registers the vibrational levels of the $X^1\Sigma^+_g$ electronic state of Na$_2$. Raman-like transitions through the $A^1\Sigma^+_u$ electronic state induce the transitions. Light fields are found that are able to implement the Fourier transform within a picosecond time scale. Such fields can be obtained by pulse-shaping techniques of a femtosecond pulse. Out of the schemes studied the square modulus scheme converges fastest. A study of the implementation of the $Q$ qubit Fourier transform in the Na$_2$ molecule was carried out for up to 5 qubits. The classical computation effort required to obtain the algorithm with a given fidelity is estimated to scale exponentially with the number of levels. The observed moderate scaling of the pulse intensity with the number of qubits in the transformation is rationalized.Comment: 32 pages, 6 figure

Two-photon coherent control of femtosecond photoassociation

Photoassociation with short laser pulses has been proposed as a technique to create ultracold ground state molecules. A broad-band excitation seems the natural choice to drive the series of excitation and deexcitation steps required to form a molecule in its vibronic ground state from two scattering atoms. First attempts at femtosecond photoassociation were, however, hampered by the requirement to eliminate the atomic excitation leading to trap depletion. On the other hand, molecular levels very close to the atomic transition are to be excited. The broad bandwidth of a femtosecond laser then appears to be rather an obstacle. To overcome the ostensible conflict of driving a narrow transition by a broad-band laser, we suggest a two-photon photoassociation scheme. In the weak-field regime, a spectral phase pattern can be employed to eliminate the atomic line. When the excitation is carried out by more than one photon, different pathways in the field can be interfered constructively or destructively. In the strong-field regime, a temporal phase can be applied to control dynamic Stark shifts. The atomic transition is suppressed by choosing a phase which keeps the levels out of resonance. We derive analytical solutions for atomic two-photon dark states in both the weak-field and strong-field regime. Two-photon excitation may thus pave the way toward coherent control of photoassociation. Ultimately, the success of such a scheme will depend on the details of the excited electronic states and transition dipole moments. We explore the possibility of two-photon femtosecond photoassociation for alkali and alkaline-earth metal dimers and present a detailed study for the example of calcium

Conceptual Inadequacy of the Shannon Information in Quantum Measurements

In a classical measurement the Shannon information is a natural measure of our ignorance about properties of a system. There, observation removes that ignorance in revealing properties of the system which can be considered to preexist prior to and independent of observation. Because of the completely different root of a quantum measurement as compared to a classical measurement conceptual difficulties arise when we try to define the information gain in a quantum measurement using the notion of Shannon information. The reason is that, in contrast to classical measurement, quantum measurement, with very few exceptions, cannot be claimed to reveal a property of the individual quantum system existing before the measurement is performed.Comment: 11 pages, 5 figures, important Ref. [6] is now cited in all appropriate place

Formation of ultracold SrYb molecules in an optical lattice by photoassociation spectroscopy: theoretical prospects

State-of-the-art {\em ab initio} techniques have been applied to compute the potential energy curves for the SrYb molecule in the Born-Oppenheimer approximation for the ground state and first fifteen excited singlet and triplet states within the coupled-cluster framework. The leading long-range coefficients describing the dispersion interactions at large interatomic distances are also reported. The electric transition dipole moments have been obtained as the first residue of the polarization propagator computed with the linear response coupled-cluster method restricted to single and double excitations. Spin-orbit coupling matrix elements have been evaluated using the multireference configuration interaction method restricted to single and double excitations with a large active space. The electronic structure data was employed to investigate the possibility of forming deeply bound ultracold SrYb molecules in an optical lattice in a photoassociation experiment using continuous-wave lasers. Photoassociation near the intercombination line transition of atomic strontium into the vibrational levels of the strongly spin-orbit mixed $b^3\Sigma^+$, $a^3\Pi$, $A^1\Pi$, and $C^1\Pi$ states with subsequent efficient stabilization into the $v^{\prime\prime}=1$ vibrational level of the electronic ground state is proposed. Ground state SrYb molecules can be accumulated by making use of collisional decay from $v^{\prime\prime}=1$ to $v^{\prime\prime}=0$. Alternatively, photoassociation and stabilization to $v^{\prime\prime}=0$ can proceed via stimulated Raman adiabatic passage provided that the trapping frequency of the optical lattice is large enough and phase coherence between the pulses can be maintained over at least tens of microseconds