We investigate the dynamics and topology of metastructures with quasiperiodically modulated local resonances. The concept is implemented on a LEGO beam featuring an array of tunable pillar-cone resonators. The versatility of the platform allows the experimental mapping of the Hofstadter-like resonant spectrum of an elastic medium, in the form of a beam waveguide. The non-trivial spectral gaps are classified by evaluating the integrated density of states of the bulk bands, which is experimentally verified through the observation of topological edge states localized at the boundaries. Results also show that the spatial location of the edge states can be varied through the selection of the phase of the resonator's modulation law. The presented results open new pathways for the design of metastructures with functionalities going beyond those encountered in periodic media by exploiting aperiodic patterning of local resonances and suggest a simple, viable platform for the observation of a variety of topological phenomena.

1.
M. Z.
Hasan
and
C. L.
Kane
, “
Colloquium: Topological insulators
,”
Rev. Mod. Phys.
82
,
3045
(
2010
).
2.
E.
Prodan
and
C.
Prodan
, “
Topological phonon modes and their role in dynamic instability of microtubules
,”
Phys. Rev. Lett.
103
,
248101
(
2009
).
3.
Z.
Yang
,
F.
Gao
,
X.
Shi
,
X.
Lin
,
Z.
Gao
,
Y.
Chong
, and
B.
Zhang
, “
Topological acoustics
,”
Phys. Rev. Lett.
114
,
114301
(
2015
).
4.
P.
Wang
,
L.
Lu
, and
K.
Bertoldi
, “
Topological phononic crystals with one-way elastic edge waves
,”
Phys. Rev. Lett.
115
,
104302
(
2015
).
5.
R.
Fleury
,
A. B.
Khanikaev
, and
A.
Alu
, “
Floquet topological insulators for sound
,”
Nat. Commun.
7
,
11744
(
2016
).
6.
J.
Lu
,
C.
Qiu
,
L.
Ye
,
X.
Fan
,
M.
Ke
,
F.
Zhang
, and
Z.
Liu
, “
Observation of topological valley transport of sound in sonic crystals
,”
Nat. Phys.
13
,
369
(
2017
).
7.
S. H.
Mousavi
,
A. B.
Khanikaev
, and
Z.
Wang
, “
Topologically protected elastic waves in phononic metamaterials
,”
Nat. Commun.
6
,
8682
(
2015
).
8.
R.
Süsstrunk
and
S. D.
Huber
, “
Observation of phononic helical edge states in a mechanical topological insulator
,”
Science
349
,
47
(
2015
).
9.
M.
Miniaci
,
R. K.
Pal
,
B.
Morvan
, and
M.
Ruzzene
, “
Experimental observation of topologically protected helical edge modes in patterned elastic plates
,”
Phys. Rev. X
8
,
031074
(
2018
).
10.
X.-L.
Qi
,
T. L.
Hughes
, and
S.-C.
Zhang
, “
Topological field theory of time-reversal invariant insulators
,”
Phys. Rev. B
78
,
195424
(
2008
).
11.
Y. E.
Kraus
and
O.
Zilberberg
, “
Quasiperiodicity and topology transcend dimensions
,”
Nat. Phys.
12
,
624
(
2016
).
12.
E.
Prodan
, “
Virtual topological insulators with real quantized physics
,”
Phys. Rev. B
91
,
245104
(
2015
).
13.
T.
Ozawa
,
H. M.
Price
,
N.
Goldman
,
O.
Zilberberg
, and
I.
Carusotto
, “
Synthetic dimensions in integrated photonics: From optical isolation to four-dimensional quantum Hall physics
,”
Phys. Rev. A
93
,
043827
(
2016
).
14.
C. H.
Lee
,
Y.
Wang
,
Y.
Chen
, and
X.
Zhang
, “
Electromagnetic response of quantum Hall systems in dimensions five and six and beyond
,”
Phys. Rev. B
98
,
094434
(
2018
).
15.
V. M.
Alvarez
and
M.
Coutinho-Filho
, “
Edge states in trimer lattices
,”
Phys. Rev. A
99
,
013833
(
2019
).
16.
M. I.
Rosa
,
R. K.
Pal
,
J. R.
Arruda
, and
M.
Ruzzene
, “
Edge states and topological pumping in spatially modulated elastic lattices
,”
Phys. Rev. Lett.
123
,
034301
(
2019
).
17.
Y. E.
Kraus
,
Y.
Lahini
,
Z.
Ringel
,
M.
Verbin
, and
O.
Zilberberg
, “
Topological states and adiabatic pumping in quasicrystals
,”
Phys. Rev. Lett.
109
,
106402
(
2012
).
18.
D. J.
Apigo
,
K.
Qian
,
C.
Prodan
, and
E.
Prodan
, “
Topological edge modes by smart patterning
,”
Phys. Rev. Mater.
2
,
124203
(
2018
).
19.
D. J.
Apigo
,
W.
Cheng
,
K. F.
Dobiszewski
,
E.
Prodan
, and
C.
Prodan
, “
Observation of topological edge modes in a quasiperiodic acoustic waveguide
,”
Phys. Rev. Lett.
122
,
095501
(
2019
).
20.
X.
Ni
,
K.
Chen
,
M.
Weiner
,
D. J.
Apigo
,
C.
Prodan
,
A.
Alù
,
E.
Prodan
, and
A. B.
Khanikaev
, “
Observation of hofstadter butterfly and topological edge states in reconfigurable quasi-periodic acoustic crystals
,”
Commun. Phys.
2
,
55
(
2019
).
21.
R. K.
Pal
,
M. I. N.
Rosa
, and
M.
Ruzzene
, “
Topological bands and localized vibration modes in quasiperiodic beams
,”
New J. Phys.
21
,
093017
(
2019
).
22.
Y.
Xia
,
A.
Erturk
, and
M.
Ruzzene
, “
Topological edge states in quasiperiodic locally resonant metastructures
,”
Phys. Rev. Appl.
13
,
014023
(
2020
).
23.
M.
Gupta
and
M.
Ruzzene
, “
Dynamics of quasiperiodic beams
,”
Crystals
10
,
1144
(
2020
).
24.
O.
Zilberberg
,
S.
Huang
,
J.
Guglielmon
,
M.
Wang
,
K. P.
Chen
,
Y. E.
Kraus
, and
M. C.
Rechtsman
, “
Photonic topological boundary pumping as a probe of 4d quantum Hall physics
,”
Nature
553
,
59
(
2018
).
25.
M.
Lohse
,
C.
Schweizer
,
H. M.
Price
,
O.
Zilberberg
, and
I.
Bloch
, “
Exploring 4d quantum Hall physics with a 2d topological charge pump
,”
Nature
553
,
55
(
2018
).
26.
M.
Rosa
,
M.
Ruzzene
, and
E.
Prodan
, “
Topological gaps by twisting
,” arXiv:2006.10019 (
2020
).
27.
I.
Petrides
,
H. M.
Price
, and
O.
Zilberberg
, “
Six-dimensional quantum Hall effect and three-dimensional topological pumps
,”
Phys. Rev. B
98
,
125431
(
2018
).
28.
D.
Thouless
, “
Quantization of particle transport
,”
Phys. Rev. B
27
,
6083
(
1983
).
29.
E.
Riva
,
M. I.
Rosa
, and
M.
Ruzzene
, “
Edge states and topological pumping in stiffness-modulated elastic plates
,”
Phys. Rev. B
101
,
094307
(
2020
).
30.
Z.-G.
Chen
,
W.
Tang
,
R.-Y.
Zhang
, and
G.
Ma
, “
Landau-Zener transition in topological acoustic pumping
,” arXiv:2008.00833 (
2020
).
31.
S.
Nakajima
,
T.
Tomita
,
S.
Taie
,
T.
Ichinose
,
H.
Ozawa
,
L.
Wang
,
M.
Troyer
, and
Y.
Takahashi
, “
Topological Thouless pumping of ultracold fermions
,”
Nat. Phys.
12
,
296
(
2016
).
32.
M.
Lohse
,
C.
Schweizer
,
O.
Zilberberg
,
M.
Aidelsburger
, and
I.
Bloch
, “
A Thouless quantum pump with ultracold bosonic atoms in an optical superlattice
,”
Nat. Phys.
12
,
350
(
2016
).
33.
I. H.
Grinberg
,
M.
Lin
,
C.
Harris
,
W. A.
Benalcazar
,
C. W.
Peterson
,
T. L.
Hughes
, and
G.
Bahl
, “
Robust temporal pumping in a magneto-mechanical topological insulator
,”
Nat. Commun.
11
(
1
),
974
(
2020
).
34.
H.
Chen
,
L.
Yao
,
H.
Nassar
, and
G.
Huang
, “
Mechanical quantum Hall effect in time-modulated elastic materials
,”
Phys. Rev. Appl.
11
,
044029
(
2019
).
35.
I.
Brouzos
,
I.
Kiorpelidis
,
F.
Diakonos
, and
G.
Theocharis
, “
Non-adiabatic time-optimal edge mode transfer on mechanical topological chain
,” arXiv:1911.03375 (
2019
).
36.
S.
Longhi
, “
Topological pumping of edge states via adiabatic passage
,”
Phys. Rev. B
99
,
155150
(
2019
).
37.
E.
Riva
,
V.
Casieri
,
F.
Resta
, and
F.
Braghin
, “
Adiabatic pumping via avoided crossings in stiffness-modulated quasiperiodic beams
,”
Phys. Rev. B
102
,
014305
(
2020
).
38.
Y.
Xia
,
E.
Riva
,
M. I.
Rosa
,
G.
Cazzulani
,
A.
Erturk
,
F.
Braghin
, and
M.
Ruzzene
, “
Experimental observation of temporal pumping in electro-mechanical waveguides
,” arXiv:2006.07348 (
2020
).
39.
W.
Cheng
,
E.
Prodan
, and
C.
Prodan
, “
Experimental demonstration of dynamic topological pumping across incommensurate bilayered acoustic metamaterials
,”
Phys. Rev. Lett.
125
,
224301
(
2020
).
40.
Z.
Liu
,
X.
Zhang
,
Y.
Mao
,
Y.
Zhu
,
Z.
Yang
,
C. T.
Chan
, and
P.
Sheng
, “
Locally resonant sonic materials
,”
Science
289
,
1734
(
2000
).
41.
D.
Yu
,
Y.
Liu
,
H.
Zhao
,
G.
Wang
, and
J.
Qiu
, “
Flexural vibration band gaps in Euler-Bernoulli beams with locally resonant structures with two degrees of freedom
,”
Phys. Rev. B
73
,
064301
(
2006
).
42.
H.
Sun
,
X.
Du
, and
P. F.
Pai
, “
Theory of metamaterial beams for broadband vibration absorption
,”
J. Intell. Mater. Syst. Struct.
21
,
1085
(
2010
).
43.
M.
Oudich
,
M.
Senesi
,
M. B.
Assouar
,
M.
Ruzenne
,
J.-H.
Sun
,
B.
Vincent
,
Z.
Hou
, and
T.-T.
Wu
, “
Experimental evidence of locally resonant sonic band gap in two-dimensional phononic stubbed plates
,”
Phys. Rev. B
84
,
165136
(
2011
).
44.
M.
Badreddine Assouar
,
M.
Senesi
,
M.
Oudich
,
M.
Ruzzene
, and
Z.
Hou
, “
Broadband plate-type acoustic metamaterial for low-frequency sound attenuation
,”
Appl. Phys. Lett.
101
,
173505
(
2012
).
45.
R.
Zhu
,
X.
Liu
,
G.
Hu
,
C.
Sun
, and
G.
Huang
, “
A chiral elastic metamaterial beam for broadband vibration suppression
,”
J. Sound Vib.
333
,
2759
(
2014
).
46.
C.
Sugino
,
Y.
Xia
,
S.
Leadenham
,
M.
Ruzzene
, and
A.
Erturk
, “
A general theory for bandgap estimation in locally resonant metastructures
,”
J. Sound Vib.
406
,
104
(
2017
).
47.
D.
Cardella
,
P.
Celli
, and
S.
Gonella
, “
Manipulating waves by distilling frequencies: A tunable shunt-enabled rainbow trap
,”
Smart Mater. Struct.
25
,
085017
(
2016
).
48.
P.
Celli
,
B.
Yousefzadeh
,
C.
Daraio
, and
S.
Gonella
, “
Bandgap widening by disorder in rainbow metamaterials
,”
Appl. Phys. Lett.
114
,
091903
(
2019
).
49.
D.
Beli
,
A. T.
Fabro
,
M.
Ruzzene
, and
J. R. F.
Arruda
, “
Wave attenuation and trapping in 3D printed cantilever-in-mass metamaterials with spatially correlated variability
,”
Sci. Rep.
9
(
1
),
5617
(
2019
).
50.
J. M.
De Ponti
,
A.
Colombi
,
E.
Riva
,
R.
Ardito
,
F.
Braghin
,
A.
Corigliano
, and
R. V.
Craster
, “
Experimental investigation of amplification, via a mechanical delay-line, in a rainbow-based metamaterial for energy harvesting
,”
Appl. Phys. Lett.
117
,
143902
(
2020
).
51.
P.
Celli
and
S.
Gonella
, “
Manipulating waves with LEGO® bricks: A versatile experimental platform for metamaterial architectures
,”
Appl. Phys. Lett.
107
,
081901
(
2015
).
52.
L.
Airoldi
and
M.
Ruzzene
, “
Design of tunable acoustic metamaterials through periodic arrays of resonant shunted piezos
,”
New J. Phys.
13
,
113010
(
2011
).
53.
C.
Sugino
,
S.
Leadenham
,
M.
Ruzzene
, and
A.
Erturk
, “
An investigation of electroelastic bandgap formation in locally resonant piezoelectric metastructures
,”
Smart Mater. Struct.
26
,
055029
(
2017
).
54.
J.
Marconi
,
E.
Riva
,
M.
Di Ronco
,
G.
Cazzulani
,
F.
Braghin
, and
M.
Ruzzene
, “
Experimental observation of nonreciprocal band gaps in a space-time-modulated beam using a shunted piezoelectric array
,”
Phys. Rev. Appl.
13
,
031001
(
2020
).
55.
W.
Cheng
,
E.
Prodan
, and
C.
Prodan
, “
Mapping the boundary weyl singularity of the 4d Hall effect via phason engineering in metamaterials
,” arXiv:2012.05130 (
2020
).

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