54 citations · 157 across the 26 of their papers we have counts for
32 papers
Quantum Mutual Information in Time
James Fullwood, Zhen Wu, Arthur J. Parzygnat +1
While the quantum mutual information is a fundamental measure of quantum information, it is only defined for spacelike-separated quantum systems. Such a limitation is not present i…
Multipartite quantum states over time from two fundamental assumptions
Seok Hyung Lie, James Fullwood
The theory of quantum states over time extends the density operator formalism into the temporal domain, providing a unified of treatment of timelike and spacelike separated systems…
Time-symmetric correlations for open quantum systems
Arthur J. Parzygnat, James Fullwood
Two-time expectation values of sequential measurements of dichotomic observables are known to be time symmetric for closed quantum systems. Namely, if a system evolves unitarily be…
General Communication Enhancement via the Quantum Switch
Zhen Wu, James Fullwood, Zhihao Ma +3
Recent studies have shown that quantum information may be effectively transmitted by a finite collection of completely depolarizing channels in a coherent superposition of differen…
Operator representation of spatiotemporal quantum correlations
James Fullwood, Arthur J. Parzygnat
While quantum correlations between two spacelike-separated systems are fully encoded by the bipartite density operator associated with the joint system, there does not exist an ana…
General covariance for quantum states over time
James Fullwood
The theory of quantum states over time provides an approach to the dynamics of quantum information which is in direct analogy with spacetime and its relation to classical dynamics.…
Virtual quantum broadcasting
Arthur J. Parzygnat, James Fullwood, Francesco Buscemi +1
The quantum no-broadcasting theorem states that it is impossible to produce perfect copies of an arbitrary quantum state, even if the copies are allowed to be correlated. Here we s…
On dynamical measures of quantum information
James Fullwood, Arthur J. Parzygnat
In this work, we use the theory of quantum states over time to define an entropy associated with quantum processes , where is a state and $\…
Quantum dynamics as a pseudo-density matrix
James Fullwood
While in relativity theory space evolves over time into a single entity known as spacetime, quantum theory lacks a standard notion of how to encapsulate the dynamical evolution of…
From time-reversal symmetry to quantum Bayes' rules
Arthur J. Parzygnat, James Fullwood
Bayes' rule is one of the simplest yet most profound, ubiquitous, and far-reaching results of classical probability theo…
On quantum states over time
James Fullwood, Arthur J. Parzygnat
In 2017, D. Horsman, C. Heunen, M. Pusey, J. Barrett, and R. Spekkens proved that there is no physically reasonable assignment that takes a quantum channel and an initial state and…
On a 2-relative entropy
James Fullwood
We construct a 2-categorical extension of the relative entropy functor of Baez and Fritz, and show that our construction is functorial with respect to vertical morphisms. Moreover,…
An axiomatic characterization of mutual information
James Fullwood
We characterize mutual information as the unique map on ordered pairs of random variables satisfying a set of axioms similar to those of Faddeev's characterization of the Shannon e…
The information loss of a stochastic map
James Fullwood, Arthur J. Parzygnat
We provide a stochastic extension of the Baez-Fritz-Leinster characterization of the Shannon information loss associated with a measure-preserving function. This recovers the condi…
On analytic groupoid cardinality
James Fullwood
Groupoids graded by the groupoid of bijections between finite sets admit generating functions which encode the groupoid cardinalities of their graded components. As suggested in th…
Orientifold limits of singular -theory vacua
James Fullwood, Dongxu Wang
We construct global orientifold limits of singular -theory vacua whose associated gauge groups are SO(3), SO(5), SO(6), , SU(4), and Spin(7). For each limit we show a unive…
On a Lefschetz-type phenomenon for elliptic Calabi--Yaus
Andrea Cattaneo, James Fullwood
We consider 18 families of elliptic Calabi--Yaus which arise in constructing -theory compactifications of string vacua, and show in each case that the upper Hodge diamond of a c…
Stringy Hirzebruch classes of Weierstrass fibrations
James Fullwood, Mark van Hoeij
A Weierstrass fibration is an elliptic fibration whose total space may be given by a global Weierstrass equation in a -bundle over . In this note, we…
On integral structure types
James Fullwood
We introduce integral structure types as a categorical analogue of virtual combinatorial species. Integral structure types then categorify power series with possibly negative coeff…
On the Sen limit squared
James Fullwood, Dongxu Wang
We introduce a class of F-theory vacua which may be viewed as a specialization of the so-called fibration, and construct a weak coupling limit associated with such vacua whic…
Towards a simple characterization of the Chern-Schwartz-MacPherson class
James Fullwood, Dongxu Wang
For a large class of possibly singular complete intersections we prove a formula for their Chern-Schwartz-MacPherson classes in terms of a single blowup along a scheme supported on…
On a relative form of Verdier Specialization
James Fullwood, Dongxu Wang
We prove a relative form of Verdier's specialization formula, and apply it to derive a Chern class identity predicted by string dualities.
On the Euler characteristic of a relative hypersurface
James Fullwood, Martin Helmer
We derive a general formula for the Euler characteristic of a fibration of projective hypersurfaces in terms of invariants of an arbitrary base variety. When the general fiber is a…
On tadpole relations via Verdier specialization
James Fullwood
Using the construct of "Verdier specialization", we provide a purely mathematical derivation of Chern class identities which upon integration yield the D3-brane tadpole relations c…