- Full text:
- PDF (eReader) / PDF (Download) (557 kB)
We numerically study quantum phase transitions and dynamical properties in the one-dimensional cluster model with several interactions by using the time-evolving block decimation method for infinite systems and the exact diagonalization. First, boundaries among several quantum phases of the model are determined from energy gap and each phase is characterized by order parameters and the entanglement spectrum (ES). We confirm that in the model with open boundary condition the degeneracy of the lowest levels in the ES corresponds to that of the ground states. Then, using the time-dependent Bogoliubov transformation with open boundary condition, we investigate dynamical properties during an interaction sweep through the critical point which separates two topological phases involving four-fold degeneracy in the ground state. After a slow sweep across the critical point, we observe spatially periodic structures in the string correlation functions and the entanglement entropy. It is shown that the periodicities stem from the Bogoliubov quasiparticles generated near the critical point.
Introduction— The exploration of topological phases such as quantum Hall states, topological insulators, and spin liquid phases has been carried out intensively for three decades. Topological phases are characterized not by any local order parameters but by nonlocal order parameters or their emergent edge excitations.1–8) Recently, it was found that entanglement can characterize topological phases.9–12) Li and Haldane proposed the concept of entanglement spectrum (ES), which is obtained from the eigenvalues of the reduced density matrix of a subsystem.13) They found that the ES of fractional quantum Hall states is similar to the energy spectrum of the low-lying excitations appearing at the edge of the system. Since then, the ES has been widely used as a tool to study topological phases.14–23)
One of the simplest models which show a variety of topological phases would be the cluster model.24–27) The ground state of the model is called the cluster state,28) which is characterized by the non-local string order parameter.26) In the case of open boundary condition, two zero-energy modes localized at each end of the system exist and four-fold-degenerate ground states result. The model is interesting also from the quantum-information perspective. In fact, one-way quantum computation and measurement-based quantum computation using the cluster state were proposed.28–30) In addition, the one-dimensional cluster model is expected to be realized in experiments of cold atoms on a zigzag ladder by introducing three-spin exchange interaction.31)
Dynamical properties of systems associated with phase transitions have been extensively studied for a long time.32–34) Dynamics during a parameter sweep across the critical point especially has been investigated.35–41) In phases characterized by conventional local order parameters, a universal relation called the Kibble–Zurek scaling33,34) is known to hold for the dynamics of defect density. However, dynamics in topological systems depends on their topological properties and differs from the Kibble–Zurek physics, as pointed out in Refs. 42–44.
In this letter, we focus on topological quantum phase transitions and dynamical properties under an interaction sweep through a critical point associated with a topological phase transition. Specifically, we generalize the cluster model in one dimension by adding interaction terms with topological nature, which give rise to a quantum phase transition between two different cluster states. Our model would be interesting in the light both of quantum-information science and of competing topological phases. We map out the ground-state phase diagram of our model by calculating energy gap and characterize the phases by order parameters and the ES. In addition, the dynamics during an interaction sweep across the critical point by calculating energy gap is investigated. For slow sweep speeds, we observe, after passing the critical point, periodic structures in the length dependence of string correlation functions and the entanglement entropy (EE). This breakdown of adiabaticity is due to the topological degeneracy of the initial cluster state. We conclude that the periodicity is attributed to the Bogoliubov quasiparticles (bogolons).
Model— The one-dimensional cluster model is defined by
The model (3,) can be solved by using spinless fermion representation.45) The original spin model (3,) is transformed into a quadratic Hamiltonian:
The topological nature of the model (3,) is clearly seen in the Majorana representation.46) The Majorana fermions
Figure 1. (Color online) (a)–(c) Schematic representation of the interactions in Eq. (3,) by the Majorana language. (a), (b), and (c) depict the first, second, and third terms of the Hamiltonian (3,). Non-interacting Majorana fermions enclosed in dotted line appear at the ends of the system. (d) Phase diagram of the generalized cluster model (3,) for
Phase diagram— In Fig. 1(d), we show the ground-state phase diagram of the model (3,) and characterize each phase by order parameters and the ES by using the method given in Ref. 48. Here we impose the periodic boundary condition. By performing the Bogoliubov transformation, the model is expressed in the momentum space as
In order to characterize each phase separated by the curves, we calculated the order parameters with the time-evolving block decimation method for infinite systems (iTEBD).49,50) This method is advantageous over the exact diagonalization for the computation of the order parameters with no boundary effect. Figure 1(e) displays the string order parameter (2,) and ferromagnetic order parameters
Let us interpret the phase diagram obtained above in terms of entanglement. Here we suppose open boundary condition and use the exact diagonalization. We divide the entire system into two subsystems A and B symmetrically around the center with the length of A being
Figure 2. (Color online) (a) Schematic of subsystems A and B. (b) ES with
Critical sweep— Now we turn to the dynamics during an interaction sweep across the critical point between C and C
Figure 3. (Color online) (a) We calculate the dual string correlation function of length
To substantiate this, we calculated the dual string correlation function for excited states. A similar periodic structure is actually observed in the length dependence of the string correlation function in the excited state with a single bogolon, as shown in Fig. 3(e). This period corresponds to the wave length of the third bogolon. As mentioned before, the bogolon with zero energy corresponds to the ground-state degeneracy. Actually, as shown in Fig. 3(e), the dual string correlation function in the bogolons with zero energy is the same as that in the Bogoliubov vacuum.
Conclusion— We have studied the one-dimensional cluster model with several interactions to understand the dynamics in the topological phase. First, we have determined the ground-state topological phase diagram (Fig. 1) and characterized each phase by the order parameters. In particular, we have found a direct quantum phase transition between two different cluster phases. We have confirmed that the degeneracy in the lowest levels of the ES in each phase corresponds to the number of the Majorana fermions existing at the edges of the system (Fig. 2). Second, we have investigated the dynamics during the interaction sweep with finite speeds across the critical point separating the two cluster states. The periodicity in the length dependence of the dual string correlation function and the EE has been observed (Fig. 3). We have reproduced similar periodic structure by using the excited states and verified that the periodicity stems from the bogolons excited when the system is close to the critical point. It would be important to see the results from the viewpoint of topological blocking.43,44) In addition, the dynamics under the periodic oscillation of an interaction parameter would be also interesting.38)
Acknowledgments
We thank Koudai Sugimoto and Ryosuke Yoshii for helpful discussions. This work was supported by JSPS KAKENHI Grant Numbers 25420698 (S.T.), 25800228 (I.D.), 25220711 (I.D.), 24540402 (K.T.). S.T. is also financially supported by Leave a Nect Co., Ltd. and Discover 21, Inc. S.T. is the Yukawa Fellow and his work is supported in part by Yukawa Memorial Foundation. The computations in the present work were performed on super computers at Yukawa Institute for Theoretical Physics, Kyoto University, and Institute for Solid State Physics, The University of Tokyo.
References
- 1 M. den Nijs and K. Rommels, Phys. Rev. B 40, 4709 (1989). 10.1103/PhysRevB.40.4709 Crossref, Google Scholar
- 2 Y. Hatsugai and M. Kohmoto, Phys. Rev. B 44, 11789 (1991). 10.1103/PhysRevB.44.11789 Crossref, Google Scholar
- 3 T. Kennedy and H. Tasaki, Phys. Rev. B 45, 304 (1992). 10.1103/PhysRevB.45.304 Crossref, Google Scholar
- 4 K. Hida, Phys. Rev. B 45, 2207 (1992). 10.1103/PhysRevB.45.2207 Crossref, Google Scholar
- 5 M. Kohmoto and H. Tasaki, Phys. Rev. B 46, 3486 (1992). 10.1103/PhysRevB.46.3486 Crossref, Google Scholar
- 6 M. Oshikawa, J. Phys.: Condens. Matter 4, 7469 (1992). 10.1088/0953-8984/4/36/019 Crossref, Google Scholar
- 7 S. Yamamoto and S. Miyashita, Phys. Rev. B 48, 9528 (1993). 10.1103/PhysRevB.48.9528 Crossref, Google Scholar
- 8 K. Totsuka and M. Suzuki, J. Phys.: Condens. Matter 7, 1639 (1995). 10.1088/0953-8984/7/8/012 Crossref, Google Scholar
- 9 A. Kitaev and J. Preskill, Phys. Rev. Lett. 96, 110404 (2006). 10.1103/PhysRevLett.96.110404 Crossref, Google Scholar
- 10 M. Levin and X. G. Wen, Phys. Rev. Lett. 96, 110405 (2006). 10.1103/PhysRevLett.96.110405 Crossref, Google Scholar
- 11 S. Furukawa and G. Misguich, Phys. Rev. B 75, 214407 (2007). 10.1103/PhysRevB.75.214407 Crossref, Google Scholar
- 12 H.-C. Jiang, Z. Wang, and L. Balents, Nat. Phys. 8, 902 (2012). 10.1038/nphys2465 Crossref, Google Scholar
- 13 H. Li and M. Haldane, Phys. Rev. Lett. 101, 010504 (2008). 10.1103/PhysRevLett.101.010504 Crossref, Google Scholar
- 14 F. Pollmann, A. M. Turner, E. Berg, and M. Oshikawa, Phys. Rev. B 81, 064439 (2010). 10.1103/PhysRevB.81.064439 Crossref, Google Scholar
- 15 K. Hasebe and K. Totsuka, Phys. Rev. B 84, 104426 (2011). 10.1103/PhysRevB.84.104426 Crossref, Google Scholar
- 16 J. I. Cirac, D. Poilblanc, N. Schuch, and F. Verstraete, Phys. Rev. B 83, 245134 (2011). 10.1103/PhysRevB.83.245134 Crossref, Google Scholar
- 17 J. Lou, S. Tanaka, H. Katsura, and N. Kawashima, Phys. Rev. B 84, 245128 (2011). 10.1103/PhysRevB.84.245128 Crossref, Google Scholar
- 18 M. Fagotti, P. Calabrese, and J. E. Moore, Phys. Rev. B 83, 045110 (2011). 10.1103/PhysRevB.83.045110 Crossref, Google Scholar
- 19 S. Tanaka, R. Tamura, and H. Katsura, Phys. Rev. A 86, 032326 (2012). 10.1103/PhysRevA.86.032326 Crossref, Google Scholar
- 20 X.-L. Qi, H. Katsura, and A. W. W. Ludwig, Phys. Rev. Lett. 108, 196402 (2012). 10.1103/PhysRevLett.108.196402 Crossref, Google Scholar
- 21 H. Nonne, M. Moliner, S. Capponi, P. Lecheminant, and K. Totsuka, Europhys. Lett. 102, 37008 (2013). 10.1209/0295-5075/102/37008 Crossref, Google Scholar
- 22 L. Cincio and G. Vidal, Phys. Rev. Lett. 110, 067208 (2013). 10.1103/PhysRevLett.110.067208 Crossref, Google Scholar
- 23 K. Shinjo, S. Sota, and T. Tohyama, Phys. Rev. B 91, 054401 (2015). 10.1103/PhysRevB.91.054401 Crossref, Google Scholar
- 24 M. Suzuki, Prog. Theor. Phys. 46, 1337 (1971). 10.1143/PTP.46.1337 Crossref, Google Scholar
- 25 S. O. Skrøvseth and S. D. Bartlett, Phys. Rev. A 80, 022316 (2009). 10.1103/PhysRevA.80.022316 Crossref, Google Scholar
- 26 P. Smacchia, L. Amico, P. Facchi, R. Fazio, G. Florio, S. Pascazio, and V. Vedral, Phys. Rev. A 84, 022304 (2011). 10.1103/PhysRevA.84.022304 Crossref, Google Scholar
- 27 R. Jafari and S. Mahdavifar, Prog. Theor. Exp. Phys. 2014, 043I02 (2014). 10.1093/ptep/ptu040 Crossref, Google Scholar
- 28 R. Raussendorf and H. J. Briegel, Phys. Rev. Lett. 86, 5188 (2001). 10.1103/PhysRevLett.86.5188 Crossref, Google Scholar
- 29 R. Raussendorf, D. E. Browne, and H. J. Briegel, Phys. Rev. A 68, 022312 (2003). 10.1103/PhysRevA.68.022312 Crossref, Google Scholar
- 30 K. Fujii, Y. Nakata, M. Ohzeki, and M. Murao, Phys. Rev. Lett. 110, 120502 (2013). 10.1103/PhysRevLett.110.120502 Crossref, Google Scholar
- 31 J. K. Pachos and M. B. Plenio, Phys. Rev. Lett. 93, 056402 (2004). 10.1103/PhysRevLett.93.056402 Crossref, Google Scholar
- 32 M. Suzuki and R. Kubo, J. Phys. Soc. Jpn. 24, 51 (1968). 10.1143/JPSJ.24.51 Link, Google Scholar
- 33 T. W. B. Kibble, J. Phys. A 9, 1387 (1976). 10.1088/0305-4470/9/8/029 Crossref, Google Scholar
- 34 W. H. Zurek, Nature 317, 505 (1985). 10.1038/317505a0 Crossref, Google Scholar
- 35 W. H. Zurek, U. Dorner, and P. Zoller, Phys. Rev. Lett. 95, 105701 (2005). 10.1103/PhysRevLett.95.105701 Crossref, Google Scholar
- 36 V. Mukherjee, U. Divakaran, A. Dutta, and D. Sen, Phys. Rev. B 76, 174303 (2007). 10.1103/PhysRevB.76.174303 Crossref, Google Scholar
- 37 J. Dziarmaga, Adv. Phys. 59, 1063 (2010). 10.1080/00018732.2010.514702 Crossref, Google Scholar
- 38 A. Das, Phys. Rev. B 82, 172402 (2010). 10.1103/PhysRevB.82.172402 Crossref, Google Scholar
- 39 A. Polkovnikov, K. Sengupta, A. Silva, and M. Vengalattore, Rev. Mod. Phys. 83, 863 (2011). 10.1103/RevModPhys.83.863 Crossref, Google Scholar
- 40 S. Suzuki, J. Inoue, and B. K. Chakrabarti, Quantum Ising Phases and Transitions in Transverse Ising Models (Springer, Heidelberg, 2013) Lecture Notes in Physics, Vol. 862. Crossref, Google Scholar
- 41 E. Canovi, E. Ercolessi, P. Naldesi, L. Taddia, and D. Vodola, Phys. Rev. B 89, 104303 (2014). 10.1103/PhysRevB.89.104303 Crossref, Google Scholar
- 42 A. Bermudez, L. Amico, and M. A. Martin-Delgado, New J. Phys. 12, 055014 (2010). 10.1088/1367-2630/12/5/055014 Crossref, Google Scholar
- 43 G. Kells, D. Sen, J. K. Slingerland, and S. Vishveshwara, Phys. Rev. B 89, 235130 (2014). 10.1103/PhysRevB.89.235130 Crossref, Google Scholar
- 44 S. Hegde, V. Shivamoggi, S. Vishveshwara, and D. Sen, arXiv:1412.5255. Google Scholar
- 45 E. Lieb, T. Schultz, and D. Mattis, Ann. Phys. 16, 407 (1961). 10.1016/0003-4916(61)90115-4 Crossref, Google Scholar
- 46 A. Y. Kitaev, Phys. Usp. 44, 131 (2001). 10.1070/1063-7869/44/10S/S29 Crossref, Google Scholar
- 47 L. Fidkowski and A. Kitaev, Phys. Rev. B 83, 075103 (2011). 10.1103/PhysRevB.83.075103 Crossref, Google Scholar
- 48 J. I. Latorre, E. Rico, and G. Vidal, Quantum Inf. Comput. 4, 48 (2004). Google Scholar
- 49 G. Vidal, Phys. Rev. Lett. 98, 070201 (2007). 10.1103/PhysRevLett.98.070201 Crossref, Google Scholar
- 50 R. Orús and G. Vidal, Phys. Rev. B 78, 155117 (2008). 10.1103/PhysRevB.78.155117 Crossref, Google Scholar
- 51 S. Montes and A. Hamma, Phys. Rev. E 86, 021101 (2012). 10.1103/PhysRevE.86.021101 Crossref, Google Scholar
- 52 S. Tanaka and S. Miyashita, Phys. Rev. E 81, 051138 (2010). 10.1103/PhysRevE.81.051138 Crossref, Google Scholar
- 53 P. W. Anderson, Phys. Rev. 110, 827 (1958). 10.1103/PhysRev.110.827 Crossref, Google Scholar
- 54 Y. Niu, S. B. Chung, C.-H. Hsu, I. Mandal, S. Raghu, and S. Chakravarty, Phys. Rev. B 85, 035110 (2012). 10.1103/PhysRevB.85.035110 Crossref, Google Scholar
- 55 E. Barouch, B. M. McCoy, and M. Dresden, Phys. Rev. A 2, 1075 (1970). 10.1103/PhysRevA.2.1075 Crossref, Google Scholar
- 56 T. Caneva, R. Fazio, and E. Santoro, Phys. Rev. B 76, 144427 (2007). 10.1103/PhysRevB.76.144427 Crossref, Google Scholar