Talk @UFF: Ivan Coulamy (UFF), Friday Oct. 9th at 11.00

Next Friday, October 9th at 11.00 in room A5- 01 we’ll have our next Infoptics group seminar at UFF. This time round our own Ivan Coulamy will talk about “Scaling of the local quantum uncertainty at quantum phase transitions”. All are welcome to attend! Please see below for an abstract.

Data: Sexta-Feira 09/10/2015, Sala A5-01, 11 am.

Palestrante: Ivan Berbert Coulamy (UFF)

Título: Scaling of the local quantum uncertainty at quantum phase transitions

Resumo: We investigate the behavior of the local quantum uncertainty (LQU) between a block of $L$ qubits and one single qubit in a composite system of $n$ qubits driven through a quantum phase transition (QPT). In this scenario, we provide an analysis of the scaling of the LQU at a first-order and a second-order QPT. For a first-order QPT, we consider a Hamiltonian implementation of the quantum search through a space of $N=2^n$ elements. By analytical evaluation, we show that the LQU exponentially saturates to a constant value at the critical point as we increase the block length $L$, with the saturation enhanced by the system size $n$. On the other hand, at non-critical points, the LQU tends to vanish for large $n$. In the case of second-order QPTs, we consider the transverse-field Ising model with open boundary conditions. By implementing a numerical analysis via density matrix renormalization group (DMRG), we show that the concavity of the LQU as a function of the block size $L$ characterizes the QPT.  For both first-order and second-order QPTs, we also consider the LQU as a function of the coupling parameter, showing that the LQU exhibits a pronounced behavior at the quantum critical point for fixed block sizes of $L$ qubits.

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