Publications

Highlights

At the end of this page, you can find the full list of publications. See also Albert’s Google Scholar.

Probing Inhomogeneous Cuprate Superconductivity by Terahertz Josephson Echo Spectroscopy

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

arXiV:2308.14849 (2023)

Photo-Induced High-Temperature Ferromagnetism in YTiO3

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

Nature 617, 7959 (2023)

Highlighted by APS Physics

See also coverage by MPSD

Towards Engineering Intrinsic Linewidths and Line-Broadening in Perovskite Nanoplatelets

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.

ACS Nano 15, 4 (2021)

Multidimensional Coherent Spectroscopy Reveals Triplet State Coherences in Cesium Lead-Halide Perovsite Nanocrystals

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.

Science Advances 7, 1 (2021)

See coverage by phys.org

Simultaneous Existence of Confined and Delocalized Vibrational Modes in Colloidal Quantum Dots

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)

 

Full list of publications

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
arXiV:2401.05503 (2024)

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)

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
arXiV:2308.14849 (2023)

An exact expression for multidimensional spectroscopy of a spin-boson Hamiltonian
A Liu.
arXiV:2311.05458 (2023)

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)