Entanglement properties of disordered quantum spin chains with long-range antiferromagnetic interactions
[1];
[2];
[3];
[6];
- Jacobs University Bremen (Germany)
- Jacobs University Bremen (Germany); Technische Universität Braunschweig (Gremany); Islamic Azad University (Iran)
- Univ. of Southern California, Los Angeles, CA (United States)
- Korea Univ., Sejong, (Korea, Republic of)
- Princeton Univ., NJ (United States); Institute for Advanced Study, Princeton, NJ (United States)
- Jacobs University Bremen (Germany); Pohang Univ. of Science and Technology (POSTECH) (Korea, Republic of)
- Univ. of Southern California, Los Angeles, CA (United States); Jacobs University Bremen (Germany)
Entanglement measures are useful tools in characterizing otherwise unknown quantum phases and indicating transitions between them. Here we examine the concurrence and entanglement entropy in quantum spin chains with random long-range couplings, spatially decaying with a power-law exponent $$\textit{α}$$. Using the strong disorder renormalization group (SDRG) technique, we find by analytical solution of the master equation a strong disorder fixed point, characterized by a fixed point distribution of the couplings with a finite dynamical exponent, which describes the system consistently in the regime $$α > \frac{1}{2}$$ . A numerical implementation of the SDRG method yields a power-law spatial decay of the average concurrence, which is also confirmed by exact numerical diagonalization. However, we find that the lowest-order SDRG approach is not sufficient to obtain the typical value of the concurrence. We therefore implement a correction scheme which allows us to obtain the leading-order corrections to the random singlet state. This approach yields a power-law spatial decay of the typical value of the concurrence, which we derive both by a numerical implementation of the corrections and by analytics. Next, using numerical SDRG, the entanglement entropy (EE) is found to be logarithmically enhanced for all $$\textit{α}$$, corresponding to a critical behavior with an effective central charge $$\textit{c}$$ = ln(2), independent of $$\textit{α}$$. This is confirmed by an analytical derivation. Using numerical exact diagonalization (ED), we confirm the logarithmic enhancement of the EE and a weak dependence on $$\textit{α}$$. For a wide range of partition size $$\textit{l}$$, the EE fits a critical behavior with a central charge close to $$\textit{c}$$ = 1, which is the same as for the clean Haldane-Shastry model with a power-law-decaying interaction with $$\textit{α}$$ = 2. Only for small $$l \ll L$$, in a range which increases with the number of spins N, we find deviations which are rather consistent with the strong disorder fixed point central charge $$\textit{c}$$ = ln(2). Furthermore, we find using ED that the concurrence shows power-law decay, albeit with smaller power exponents than obtained by SDRG. Finally, we also present results obtained with DMRG and find agreement with ED for sufficiently small $$\textit{α}$$ < 2, whereas for larger $$\textit{α}$$ DMRG tends to underestimate the entanglement entropy and finds a faster decaying concurrence.
- Research Organization:
- Univ. of Southern California, Los Angeles, CA (United States); Princeton Univ., NJ (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); German Research Foundation (DFG); National Research Foundation of Korea (NRF)
- Grant/Contract Number:
- FG02-05ER46240; SC0002140; NRF- 2020R1I1A3074769
- OSTI ID:
- 1849672
- Journal Information:
- Physical Review. B, Vol. 102, Issue 21; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Beyond universal behavior in the one-dimensional chain with random nearest-neighbor hopping
Fidelity and entanglement entropy for infinite-order phase transitions