Exponentially enhanced quantum metrology.

We show that when a suitable entanglement-generating unitary operator depending on a parameter is applied on N qubits in parallel, a precision of the order of 2(-N) in estimating the parameter may be achieved. This exponentially improves the precision achievable in classical and in quantum nonentangling strategies.

Preserving quantum states using inverting pulses: a super-Zeno effect.

We construct an algorithm for suppressing the transitions of a quantum mechanical system, initially prepared in a subspace P of the full Hilbert space of the system, to outside this subspace by subjecting it to a sequence of unequally spaced short-duration pulses. Each pulse multiplies the amplitude of the vectors in the subspace by -1. The number of pulses required by the algorithm to limit the leakage probability to epsilon in time increases as T exp[square root log(T(2)/epsilon)], compared to T(2)epsilon(-1) in the standard quantum Zeno effect.

Multipartite separability inequalities exponentially stronger than local reality inequalities.

I show that separability of N-partite quantum states implies new inequalities on Bell correlations which are stronger than the corresponding Mermin-Roy-Singh local reality inequalities by a factor of 2((N-1)/2).

Health services in Gaza under the autonomy plan.

The Gaza Strip now has limited self-rule. Its people inherit a health-care system provided by four sectors--the Israeli government, the UN Relief and Works Agency, non-governmental organisations, and private facilities. They also inherit a legacy of health indices comparing unfavourably with those of Israel, huge numbers of refugees, a looming water crisis, civil unrest, and a health care expenditure bill (as a proportion of gross domestic product) that will be unsustainable. Four plans have been drawn up for health services in autonomous Gaza but none is exactly right.