## Profile
Quantum Information Science ## Outputs
Title | Category | Date | Authors |
Strategies for measurement-based quantum computation with cluster states transformed by stochastic local operations and classical communication University of Calgary | Publication | 2011-10-01 | A. D'Souza, D. Feder | SLOCC equivalence of graph states and Hamiltonian ground statesMeasurement-based quantum computation (MBQC) requires a massively entangled resource state (such as a cluster state) as input. Experimental efforts towards generating such states have typically focused on performing global entangling operations on uncorrelated qubits. As the states that result from this type of procedure are not generally ground states, they are very sensitive to decoherence effects. A more robust resource would be one that is in fact a ground state of some Hamiltonian that exhibits a reasonably large energy gap between the ground state and the various excited states. We discuss the possibility of finding simple two-body Hamiltonians whose ground states are equivalent to resource states for MBQC under stochastic protocols comprised solely of local operations and classical communication. University of Calgary | Presentation | 2008-02-15 | A. D'Souza, D. Feder | SLOCC-Equivalence of Pure States and Graph StatesMeasurement-based quantum computation (MBQC) is a model of quantum computing allowing for information processing by means of adaptive local measurements on a resource state. This resource state is a massively entangled many-body state, the best known example of which is the cluster state. While the cluster is not itself a non-degenerate ground state of a realistic Hamiltonian, other resources that are equivalent to the cluster under stochastic local operations and classical communication (SLOCC) may be. We describe a protocol for determining SLOCC-equivalence between arbitrary pure states and graph states, a generalization of cluster states. University of Calgary | Presentation | 2010-02-19 | A. D'Souza, J. Briët, D. Feder | Strategies for measurement-based quantum computation with SLOCC-transformed cluster statesUniversal quantum computation can be accomplished via projective single-qubit measurements on a highly entangled resource state, together with classical feedforward of the measurement results. The best-known example of such a resource state is the cluster state, on which judiciously chosen single-qubit measurements can be used to simulate an arbitrary quantum circuit with a number of measurements that is linear in the number of gates. We examine the power of the orbit of cluster states under GL(2,C), also known as the SLOCC-equivalence class, as a resource for universal computation driven strictly by projective measurements. We identify circumstances under which such states constitute resources for random-length computation, in one case quasi-deterministically and in another probabilistically. University of Calgary | Presentation | 2011-02-18 | A. D'Souza, D. Feder | Ground states as resources for universal measurement-based quantum computingMeasurement-based quantum computation (MBQC) requires a massively entangled resource state (such as a cluster state) as input. Experimental efforts towards generating such states have typically focused on performing global entangling operations on uncorrelated qubits. As the states that result from this type of procedure are not generally ground states, they are very sensitive to decoherence effects. A more robust resource would be one that is in fact a ground state of some Hamiltonian that exhibits a reasonably large energy gap between the ground state and the various excited states. We will discuss the possibility of finding simple two-body spin Hamiltonians whose ground states are equivalent to resource states for MBQC under stochastic protocols comprised solely of local operations and classical communication.
University of Calgary | Presentation | 2008-03-11 | A. D'Souza, D. Feder | (Almost) No entanglement is needed for deterministic single-qubit gate teleportationComputers having access to quantum entanglement are widely believed to be more powerful than those that do not. Quantum states that are
entangled have been shown to be resources for a vast array of information processing tasks. One such task is gate teleportation, wherein arbitrary single-qubit operations can be effected
deterministically by means of local measurements on a highly entangled resource state. We will show that, under certain circumstances, deterministic gate teleportation can still be accomplished using resource states that are locally almost pure. University of Calgary | Presentation | 2010-07-16 | A. D'Souza, D. Feder | Superfluid to Mott-Insulator Transition in Thermodynamic Limit of 1D Coupled Cavity Array University of Calgary | Presentation | 2012-02-29 | A. D'Souza, B. C. Sanders, D. Feder | Fermionic resources for quantum teleportationThe measurement-based quantum computing (MBQC) model requires the
creation of a massively entangled ``resource state,'' on which
computation proceeds via single-qubit measurements. Although 2D
resource states are believed necessary for universal MBQC, 1D states
can serve as resources for certain tasks as well, such as quantum
teleportation. One possible route to a resource state is to cool a
gapped, two-body system whose ground state encodes the resource. I
will discuss our recent work in this area, in which we investigate
candidate fermionic systems using the Density Matrix Renormalization
Group method and the Matrix Product States description of highly
entangled 1D states. University of Calgary | Presentation | 2010-03-18 | A. D'Souza, D. Feder | Deterministic random-length computation with weakly entangled cluster statesUniversal quantum computation can be accomplished via single-qubit measurements on a highly entangled resource state, together with classical feedforward of the measurement results. The best-known example of such a resource state is the cluster state, on which judiciously chosen single-qubit measurements can be used to simulate an arbitrary quantum circuit with a number of measurements that is linear in the number of gates. We examine the power of the orbit of the cluster states under GL(2,C), also known as the SLOCC equivalence class of the cluster state, as a resource for deterministic universal computation. We find that, under certain circumstances, these states do indeed constitute resources for such computations, but of random length. University of Calgary | Presentation | 2011-03-21 | A. D'Souza, D. Feder | Tonks-Girardeau phase in 1D coupled cavity arrays University of Calgary | Presentation | 2012-05-29 | A. D'Souza, B. C. Sanders, D. Feder | Fermionized photons in one-dimensional coupled cavitiesWe consider the properties of a one-dimensional array of evanescently coupled high-finesse cavities each containing a single neutral atom, in the limit of low photon densities. The ground state of the corresponding Jaynes-Cummings-Hubbard (JCH) model is obtained numerically using the Density Matrix Renormalization Group algorithm. We find strong evidence for the existence of a Tonks-Girardeau phase, in which the photons are strongly fermionized, between the Mott-insulating and superfluid phases as a function of the inter-cavity coupling. Results for photon and spin excitation densities, one- and two-body correlation functions, and superfluid and condensate fractions are all found to be consistent with this conclusion. University of Calgary | Presentation | 2014-03-05 | D. Feder, A. D'Souza, B. C. Sanders |
| |