The bipartite entanglement entropy of a segment of length $l$ in $1+1$ -dimensional conformal field theories (CFT) follows the formula $S=\frac{c}{3}\mathrm{ln}l+\ensuremath{\gamma}$, where $c$ is the central charge of the CFT and $\ensuremath{\gamma}$ is a cutoff-dependent constant which diverges in the absence of an ultraviolet cutoff. According to this formula, systems with larger central charges have more bipartite entanglement entropy. Using quantum Fisher information (QFI), we argue that systems with bigger central charges not only have larger bipartite entanglement entropy, but also have more multipartite entanglement content. In particular, we argue that since a system with a smaller smallest scaling dimension has a larger QFI, the multipartite entanglement content of a CFT is dependent on the value of the smallest scaling dimension present in the spectrum of the system. We show that our argument seems to be consistent with some of the existing results regarding the von Neumann entropy, negativity, and localizable entanglement in $1+1$ dimensions. Furthermore, we also argue that the QFI decays under renormalization group flow between two unitary CFTs. Finally, we also comment on nonconformal but scale-invariant systems.The bipartite entanglement entropy of a segment of length $l$ in $1+1$-dimensional conformal field theories (CFT) follows the formula $S=\frac{c}{3}\mathrm{ln}l+\ensuremath{\gamma}$, where $c$ is the central charge of the CFT and $\ensuremath{\gamma}$ is a cutoff-dependent constant which diverges in the absence of an ultraviolet cutoff. According to this formula, systems with larger central charges have more bipartite entanglement entropy. Using quantum Fisher information (QFI), we argue that systems with bigger central charges not only have larger bipartite entanglement entropy, but also have more multipartite entanglement content. In particular, we argue that since a system with a smaller smallest scaling dimension has a larger QFI, the multipartite entanglement content of a CFT is dependent on the value of the smallest scaling dimension present in the spectrum of the system. We show that our argument seems to be consistent with some of the existing results regarding the von Neumann entropy, negativity, and localizable entanglement in $1+1$ dimensions. Furthermore, we also argue that the QFI decays under renormalization group flow between two unitary CFTs. Finally, we also comment on nonconformal but scale-invariant systems.

arXiv:1705.03544Physical review. D/Physical review. D.Dec 13, 201713 citations

A larger quantum alphabet

Roberto Osellame

NatureJun 1, 20172 citations

Influences of Compton scattering on soliton squeezed state transmission in fiber

Zhang Xiao-Fu

Using the nonlinear quantum theory and revised Schr(?)dinger equation,the influences of the multi-photon nonlinear Compton scattering on the propagation of the soliton squeezed state in the fiber are studied,and the squeezing ratio of the soliton propagation is given out.The results show that near the ideal first-order soliton,the scattering can make the smallest soliton squeezed ratio with the increase of the soliton pulse amplitude,that is to say the larger soliton squeezed state can be gotten.With the increase of the loss,the squeezed degree of the squeezed state slowly decreases.When the loss is same,the transmission distance to get the smallest soliton squeezed ratio is shorter than that before the scattering with the increase of the soliton pulse amplitude.Using the nonlinear quantum theory and revised Schr(?)dinger equation,the influences of the multi-photon nonlinear Compton scattering on the propagation of the soliton squeezed state in the fiber are studied,and the squeezing ratio of the soliton propagation is given out.The results show that near the ideal first-order soliton,the scattering can make the smallest soliton squeezed ratio with the increase of the soliton pulse amplitude,that is to say the larger soliton squeezed state can be gotten.With the increase of the loss,the squeezed degree of the squeezed state slowly decreases.When the loss is same,the transmission distance to get the smallest soliton squeezed ratio is shorter than that before the scattering with the increase of the soliton pulse amplitude.

Chinese Journal of Quantum ElectronicsJan 1, 20080 citations

Quantum at Scale

Joseph S. Broz, Irfan A. Siddiqi, Darı́o Gil

PhysicsSep 21, 20200 citations

An experimentally testable proof of the discreteness of time

Guang Ping He

By proposing a paradox between the impossibility of superluminal signal transfer and the normalization condition of wavefunctions, we predict that when a change happens to the conditions that determining the status of a quantum system, the system will show no response to this change at all, until after a certain time interval. Otherwise either special relativity or quantum mechanics will be violated. As a consequence, no physical process can actually happen within Planck time. Therefore time is discrete, with Planck time being the smallest unit. More intriguingly, systems with a larger size and a slower speed will have a larger unit of time. Unlike many other interpretations of the discreteness of time, our proof can be tested, at less partly, by experiments. Our result also sets a limit on the speed of computers, and gives instruction to the search of quantum gravity theories.By proposing a paradox between the impossibility of superluminal signal transfer and the normalization condition of wavefunctions, we predict that when a change happens to the conditions that determining the status of a quantum system, the system will show no response to this change at all, until after a certain time interval. Otherwise either special relativity or quantum mechanics will be violated. As a consequence, no physical process can actually happen within Planck time. Therefore time is discrete, with Planck time being the smallest unit. More intriguingly, systems with a larger size and a slower speed will have a larger unit of time. Unlike many other interpretations of the discreteness of time, our proof can be tested, at less partly, by experiments. Our result also sets a limit on the speed of computers, and gives instruction to the search of quantum gravity theories.

arXiv:0911.2416Nov 12, 20092 citations

The bipartite entanglement entropy of a segment of length

l

1+1

-dimensional conformal field theories (CFT) follows the formula $S=\frac{c}{3}\mathrm{ln}l+\ensuremath{\gamma}$, where

c

is the central charge of the CFT and $\ensuremath{\gamma}$ is a cutoff-dependent constant which diverges in the absence of an ultraviolet cutoff. According to this formula, systems with larger central charges have more bipartite entanglement entropy. Using quantum Fisher information (QFI), we argue that systems with bigger central charges not only have larger bipartite entanglement entropy, but also have more multipartite entanglement content. In particular, we argue that since a system with a smaller smallest scaling dimension has a larger QFI, the multipartite entanglement content of a CFT is dependent on the value of the smallest scaling dimension present in the spectrum of the system. We show that our argument seems to be consistent with some of the existing results regarding the von Neumann entropy, negativity, and localizable entanglement in

1+1

dimensions. Furthermore, we also argue that the QFI decays under renormalization group flow between two unitary CFTs. Finally, we also comment on nonconformal but scale-invariant systems.