27 citations · 79 across the 9 of their papers we have counts for
9 papers · 1 filter
Decoherence without the state: A causal quantum Darwinist approach
Nick Ormrod, Tein van der Lugt, Yìlè Yīng +1
The consistent histories formalism can be used to describe histories comprised of events across many systems, times, and places, plausibly rich enough to describe our experiences o…
A causal derivation of the algebraic approach to quantum systems
Nick Ormrod
It is commonly assumed that every quantum system is represented by some algebra of operators. Doubt is cast on this assumption by what appears, at first glance, to be a reasonable…
Quantum influences and event relativity
Nick Ormrod, Jonathan Barrett
We develop a new interpretation of quantum theory by combining insights from extended Wigner's friend scenarios and quantum causal modelling. In this interpretation, which synthesi…
Possibilistic and maximal indefinite causal order in the quantum switch
Tein van der Lugt, Nick Ormrod
It was recently found that the indefinite causal order in the quantum switch can be certified device-independently when assuming the impossibility of superluminal influences. Here…
On the Origin of Linearity and Unitarity in Quantum Theory
Matt Wilson, Nick Ormrod
We reconstruct the transformations of quantum theory using a physically motivated postulate. This postulate states that transformations should be locally applicable, and recovers t…
Which theories have a measurement problem?
Nick Ormrod, V. Vilasini, Jonathan Barrett
It is shown that any theory that has certain properties has a measurement problem, in the sense that it makes predictions that are incompatible with measurement outcomes being abso…
A no-go theorem for absolute observed events without inequalities or modal logic
Nick Ormrod, Jonathan Barrett
This paper builds on no-go theorems to the effect that quantum theory is inconsistent with observations being absolute; that is, unique and non-relative. Unlike the existing no-go…
Consistent circuits for indefinite causal order
Augustin Vanrietvelde, Nick Ormrod, Hlér Kristjánsson +1
Over the past decade, a number of quantum processes have been proposed which are logically consistent, yet feature a cyclic causal structure. However, there is no general formal me…
Causal structure in the presence of sectorial constraints, with application to the quantum switch
Nick Ormrod, Augustin Vanrietvelde, Jonathan Barrett
Existing work on quantum causal structure assumes that one can perform arbitrary operations on the systems of interest. But this condition is often not met. Here, we extend the fra…