TY - JOUR
T1 - Entanglement enhances cooling in microscopic quantum refrigerators
JF - Physical Review E
Y1 - 2014
A1 - Nicolas Brunner
A1 - Huber, Marcus
A1 - Noah Linden
A1 - Sandu Popescu
A1 - Ralph Silva
A1 - Paul Skrzypczyk
AB - Small self-contained quantum thermal machines function without external source of work or control, but using only incoherent interactions with thermal baths. Here we investigate the role of entanglement in a small self-contained quantum refrigerator. We first show that entanglement is detrimental as far as efficiency is concerned---fridges operating at efficiencies close to the Carnot limit do not feature any entanglement. Moving away from the Carnot regime, we show that entanglement can enhance cooling and energy transport. Hence a truly quantum refrigerator can outperform a classical one. Furthermore, the amount of entanglement alone quantifies the enhancement in cooling.
VL - 89
IS - 3
JO - Phys. Rev. E
ER -
TY - JOUR
T1 - Inequalities for the ranks of multipartite quantum states
JF - Linear Algebra and its Applications
Y1 - 2014
A1 - Josh Cadney
A1 - Huber, Marcus
A1 - Noah Linden
A1 - Winter, Andreas
AB - We investigate relations between the ranks of marginals of multipartite quantum states. These are the Schmidt ranks across all possible bipartitions and constitute a natural quantification of multipartite entanglement dimensionality. We show that there exist inequalities constraining the possible distribution of ranks. This is analogous to the case of von Neumann entropy (\alpha-R\'enyi entropy for \alpha=1), where nontrivial inequalities constraining the distribution of entropies (such as e.g. strong subadditivity) are known. It was also recently discovered that all other \alpha-R\'enyi entropies for α∈(0,1)∪(1,∞) satisfy only one trivial linear inequality (non-negativity) and the distribution of entropies for α∈(0,1) is completely unconstrained beyond non-negativity. Our result resolves an important open question by showing that also the case of \alpha=0 (logarithm of the rank) is restricted by nontrivial linear relations and thus the cases of von Neumann entropy (i.e., \alpha=1) and 0-R\'enyi entropy are exceptionally interesting measures of entanglement in the multipartite setting.
VL - 452
JO - Linear Algebra and its Applications
ER -
TY - Generic
T1 - The Quantum Entropy Cone of Stabiliser States
T2 - 8th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2013)
Y1 - 2013
A1 - Noah Linden
A1 - Frantisek Matus
A1 - Mary Beth Ruskai
A1 - Winter, Andreas
ED - Severini, Simone
ED - Fernando Brandao
JF - 8th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2013)
T3 - LIPICS
CY - Guelph, ON
VL - 22
ER -