At the end of this page, you can find the full list of publications. See also Albert’s Google Scholar.
The superconducting gap in high-Tc cuprates is known to exhibit spatial inhomogeneity. It is unknown however, how disorder of the superconducting gap translates to disorder of the superconducting phase. To address this question we developed 2-D terahertz spectroscopy in a non-collinear geometry for the first time, allowing us to study interlayer tunneling nonlinearities in single-crystal LSCO.
A Liu, D Pavicevic, MH Michael, AG Salvador, PE Dolgirev, M Fechner, AS Disa, PM Lozano, Q Li, GD Gu, E Demler, and A Cavalleri
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In open quantum systems, coupling between system and bath degrees of freedom are a primary source of quantum decoherence. Multidimensional coherent spectroscopy (MDCS) is a powerful technique capable of directly probing the spectral density of the system–bath coupling. To simplify modeling of MDCS of an open quantum system, we derive a compact, exact expression for multidimensional spectra of a spin-boson Hamiltonian.
A Liu.
Advanced Quantum Technologies 7, 3 (2024)
YTiO3 is a low-temperature ferromagnet in which orbital fluctuations lower the Curie temperature. Here, we used a strong-field terahertz light field to resonantly excite a vibrational mode that results in a remarkable threefold increase in the Curie temperature. This effect is attributed to a light-induced suppression of orbital fluctuations that manifests as metastable ferromagnetism persisting for nanoseconds.
AS Disa, J Curtis, M Fechner, A Liu, A von Hoegen, M Forst, TF Nova, P Narang, A Maljuk, AV Boris, B Keimer, and A Cavalleri
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Colloidal nanoplatelets are often claimed to be homogeneously broadened due to the dominant out-of-plane quantum confinement. To validate this claim we use 2-D spectroscopy to simultaneously resolve homogeneous and inhomogeneous exciton linewidths in CsPbI3 perovskite nanoplatelets. These linewidths are resolved as a function of temperature, excitation power, and exciton resonance energy to provide design criteria for engineering optoelectronic properties for applications.
A Liu, G Nagamine, LG Bonato, DB Almeida, LF Zagonel, AF Nogueira, LA Padilha, and ST Cundiff.
The exciton manifold in lead-halide perovskite nanocrystals is claimed to host “bright-triplet” excitons that contribute to their remarkable luminescence efficiencies. However, signatures of these bright-triplet excitons are normally obscured by dominant inhomogeneous broadening. To circumvent this issue, we use polarization-resolved 2-D spectroscopy to extract the intrinsic exciton lineshape in an ensemble and find evidence of an interleaved “partially-bright” exciton manifold.
A Liu, DB Almeida, LG Bonato, G Nagamine, LF Zagonel, AF Nogueira, LA Padilha, and ST Cundiff.
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The spectral density of exciton-phonon coupling is a quantity that is difficult to measure directly. We apply 2-D spectroscopy at cryogenic temperatures to resolve the spectral density in CdSe colloidal quantum dots, which in turn reveals confined vibrational modes from the nanometer-size dot geometry.
A Liu, DB Almeida, W-K Bae, LA Padilha, and ST Cundiff.
Journal of Physical Chemistry Letters 10, 20 (2019)
Squeezed Josephson plasmons in driven YBa2Cu3O6+x
N Taherian, M Först, A Liu, M Fechner, D Pavicevic, A von Hoegen, E Rowe, Y Liu, S Nakata, B Keimer, E Demler, MH Michael, and A Cavalleri
arXiV:2401.01115 (2024)
Principles of 2D terahertz spectroscopy of collective excitations: the case of Josephson plasmons in layered superconductors
AG Salvador, PE Dolgirev, MH Michael, A Liu, D Pavicevic, M Fechner, A Cavalleri, and E Demler
Physical Review B 110, 9 (2024)
Probing Inhomogeneous Cuprate Superconductivity by Terahertz Josephson Echo Spectroscopy
A Liu, D Pavicevic, MH Michael, AG Salvador, PE Dolgirev, M Fechner, AS Disa, PM Lozano, Q Li, GD Gu, E Demler, and A Cavalleri
Nature Physics, (2024)
Excitation-Dependent Features and Artifacts in 2-D Terahertz Spectroscopy
A Liu and A Disa
Optics Express 32, 16 (2024)
An exact expression for multidimensional spectroscopy of a spin-boson Hamiltonian
A Liu.
Advanced Quantum Technologies 7, 3 (2024)
Off-axis imaging with off-axis parabolic mirrors
A Liu.
Applied Optics 62, 32 (2023)
Measuring exciton-phonon coupling in semiconductor nanocrystals
A Liu, DB Almeida, LA Padilha, and ST Cundiff.
Electronic Structure 5, 3 (2023)
Photo-Induced High-Temperature Ferromagnetism in YTiO3
AS Disa, J Curtis, M Fechner, A Liu, A von Hoegen, M Forst, TF Nova, P Narang, A Maljuk, AV Boris, B Keimer, and A Cavalleri
Nature 617, 7959 (2023)
Perspective: Multi-Dimensional Coherent Spectroscopy of Perovskite Nanocrystals
A Liu, DB Almeida, LA Padilha, and ST Cundiff.
JPhys Materials 5, 2 (2022)
Measuring Exciton Fine-Structure in Randomly Oriented Perovskite Nanocrystal Ensembles Using Nonlinear Optical Spectroscopy: Theory
A Liu.
Nanomaterials 12, 5 (2022)
Towards Engineering Intrinsic Linewidths and Line-Broadening in Perovskite Nanoplatelets
A Liu, G Nagamine, LG Bonato, DB Almeida, LF Zagonel, AF Nogueira, LA Padilha, and ST Cundiff.
ACS Nano 15, 4 (2021)
Spectral Broadening and Ultrafast Dynamics of a Nitrogen-Vacancy Center Ensemble in Diamond
A Liu, ST Cundiff, DB Almeida, and R Ulbricht.
Materials for Quantum Technology 1, 2 (2021)
Multidimensional Coherent Spectroscopy Reveals Triplet State Coherences in Cesium Lead-Halide Perovsite Nanocrystals
A Liu, DB Almeida, LG Bonato, G Nagamine, LF Zagonel, AF Nogueira, LA Padilha, and ST Cundiff.
Science Advances 7, 1 (2021)
Spectroscopic Signatures of Electron-Phonon Coupling in Silicon-Vacancy Centers in Diamond
A Liu and ST Cundiff.
Physical Review Materials 4, 5 (2020)
Communication: Effect of Dimensionality on the Optical Absorption Properties of CsPbI3 Perovskite Nanocrystals
A Liu, LG Bonato, F Sessa, DB Almeida, E Isele, G Nagamine, LF Zagonel, AF Nogueira, LA Padilha, and ST Cundiff.
Journal of Chemical Physics 151, 19 (2019)
Simultaneous Existence of Confined and Delocalized Vibrational Modes in Colloidal Quantum Dots
A Liu, DB Almeida, W-K Bae, LA Padilha, and ST Cundiff.
Journal of Physical Chemistry Letters 10, 20 (2019)
Non-Markovian Exciton-Phonon Interactions in Core-Shell Colloidal Quantum Dots at Femtosecond Timescales
A Liu, DB Almeida, W-K Bae, LA Padilha, and ST Cundiff
Physical Review Letters 123, 5 (2019)
High Resolution Nonlinear Optical Spectroscopy of InGaN Quantum Dots in GaN Nanowires
C Nelson, S Deshpande, A Liu, S Jahangir, P Bhattacharya, and DG Steel.
JOSA B 34, 6 (2017)