# Decay of correlations in long-range interacting systems at non-zero temperature

Date and time |
Feb 15, 2019 from 11:00 AM to 12:00 PM |
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Location | 60 St. George Street, MP 408 |

Host | Daniel James/Aaron Goldberg |

## Senaida Hernandez

**
ICFO, Quantum Information Theory Group
**

We study correlations in fermionic systems with long-range interactions in thermal equilibrium. We prove an upper-bound on the correlation decay between anti-commut-ing operators based on long-range Lieb-Robinson type bounds. Our result shows that correlations between such operators in fermionic long-range systems of spatial dimension $D$ with at most two-site interactions decaying algebraically with the distance with an exponent $\alpha \geq 2\,D$, decay at least algebraically with an exponent arbitrarily close to $\alpha$. Our bound is asymptotically tight, which we demonstrate by numerically analysing density-density correlations in a 1D quadratic (free, exactly solvable) model, the Kitaev chain with long-range interactions. Away from the quantum critical point correlations in this model are found to decay asymptotically as slowly as our bound permits.

Contact Name | Helen Iyer |
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