<i>Mécanique quantique, Vol. 2</i> and <i>Quantum Mechanics</i>

Messiah, Albert; Temmer, G. M.; Potter, J. H.; Chako, Nicholas

doi:10.1063/1.3051398

Cited by 135 publications

(219 citation statements)

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“…The identification of the two parts of equation (6) with spin and orbital angular momenta is tempting due to the appearance of the operator L = −ir × ∇ and the relationship of the cross-product in S t with the spin-1 matrices representing S. But, since L and S are not operators in M, the question arises of which are the operators corresponding to the two parts of equation (6). In his book on Quantum Mechanics, Messiah [22,Ch. XXI,problem 7] offers an expression which corresponds to the second quantization of the first part of equation (6).…”

Section: The Separation Of L and Smentioning

confidence: 99%

Helicity and angular momentum: A symmetry-based framework for the study of light-matter interactions

2012

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We propose a new theoretical and practical framework for the study of light-matter interactions and the angular momentum of light. Our proposal is based on helicity, total angular momentum, and the use of symmetries. We compare the new framework to the current treatment, which is based on separately considering spin angular momentum and orbital angular momentum and using the transfer between the two in physical explanations. In our proposal, the fundamental problem of spin and orbital angular momentum separability is avoided, predictions are made based on the symmetries of the systems, and the practical application of the concepts is straightforward. Finally, the framework is used to show that the concept of spin to orbit transfer applied to focusing and scattering is masking two completely different physical phenomena related to the breaking of different fundamental symmetries: transverse translational symmetry in focusing and electromagnetic duality symmetry in scattering.

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Section: The Separation Of L and Smentioning

confidence: 99%

Helicity and angular momentum: A symmetry-based framework for the study of light-matter interactions

2012

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“…Note that this current is independent of the potential V (φ) and up to a prefactor, it is just the momentum density of the boson field 43 . Consequently, translation invariance implies that the total thermal current J e is conserved.…”

Section: E the Massive Boson Modelmentioning

confidence: 99%

Thermal transport in one-dimensional spin gap systems

2003

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We study thermal transport in one dimensional spin systems both in the presence and absence of impurities. In the absence of disorder, all these spin systems display a temperature dependent Drude peak in the thermal conductivity. In gapless systems, the low temperature Drude weight is proportional to temperature and to the central charge which characterizes the conformal field theory that describes the system at low energies. On the other hand, the low temperature Drude weight of spin gap systems shows an activated behavior modulated by a power law. For temperatures higher than the spin gap, one recovers the linear T behavior akin to gapless systems. For temperatures larger than the exchange coupling, the Drude weight decays as T −2 . We argue that this behavior is a generic feature of quasi one dimensional spin gap systems with a relativistic-like low energy dispersion. We also consider the effect of a magnetic field on the Drude weight with emphasis on the commensurate-incommensurate transition induced by it. We then study the effect of nonmagnetic impurities on the thermal conductivity of the dimerized XY chain and the spin-1 2 two leg ladder. Impurities destroy the Drude peak and the thermal conductivity exhibits a purely activated behavior at low temperature, with an activation gap renormalized by disorder. The relevance of these results for experiments is briefly discussed.

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“…Using the Baker-Campbell-Hausdorff formula (see, e.g. [15]), in the permuted computational basis the quantum evolution is described by the two decoupled equations…”

Section: Typical Class Of Constraintsmentioning

confidence: 99%

Time-optimal unitary operations

et al. 2007

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Extending our previous work on time optimal quantum state evolution [A. Carlini, A. Hosoya, T. Koike and Y. Okudaira, Phys. Rev. Lett. 96, 060503 (2006)], we formulate a variational principle for finding the time optimal realization of a target unitary operation, when the available Hamiltonians are subject to certain constraints dictated either by experimental or by theoretical conditions. Since the time optimal unitary evolutions do not depend on the input quantum state this is of more direct relevance to quantum computation. We explicitly illustrate our method by considering the case of a two-qubit system self-interacting via an anisotropic Heisenberg Hamiltonian and by deriving the time optimal unitary evolution for three examples of target quantum gates, namely the swap of qubits, the quantum Fourier transform and the entangler gate. We also briefly discuss the case in which certain unitary operations take negligible time.

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Mécanique quantique, Vol. 2 and Quantum Mechanics

Cited by 135 publications

References 0 publications

Helicity and angular momentum: A symmetry-based framework for the study of light-matter interactions

Helicity and angular momentum: A symmetry-based framework for the study of light-matter interactions

Thermal transport in one-dimensional spin gap systems

Time-optimal unitary operations

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