Project A07: Physical Review Letter 2017

Parametric Oscillation, Frequency Mixing, and Injection Locking of Strongly Coupled Nanomechanical Resonator Modes

Enforcing discipline on nanomechanical vibration

When one strongly shakes a pendulum close to its resonance frequency, it eventually locks to the shaking, i.e. tightly follows the applied force. Here we investigate such phenomena for two orthogonal vibrations of a nanomechanical string resonator which is five hundred times smaller than a human hair and embedded in an all...

Read more

Project C04: Physical Review B 2017

Strong paramagnon scattering in single atom Pd contacts

Among all transition metals, palladium (Pd) has the highest density of states at the Fermi energy at low temperatures yet does not fulfill the Stoner criterion for ferromagnetism. However, close proximity to magnetism renders it a nearly ferromagnetic metal, which hosts paramagnons, strongly damped spin fluctuations. Here we compare the total and the differential conductance of monoatomic contacts consisting of single Pd and cobalt (Co)...

Read more

Project A01: Physical Review 2017 (Editors' Suggestion)

Acoustic waves undetectable by transient reflectivity measurements

In laser ultrasonics, ultrashort light pulses generate coherent acoustic pulses of picosecond duration via multiple possible physical mechanisms, involving optoacoustic conversion processes. These wide-band GHz acoustic signals are optically detected at the sample surfaces by ultrafast time-delayed probe light pulses. When the coherent acoustic pulses in GaAS are detected via the Brillouin scattering of probe light pulses of 400...

Read more

Project C13/C14 - Chem. Eur. Journal

Redox-Active Tetraruthenium Macrocycles Built from 1,4-Divinylphenylene-Bridged Diruthenium Complexes

Metallamacrocylic tetraruthenium complexes were generated by treatment of 1,4-divinylphenylene-bridged diruthenium complexes with functionalized 1,3-benzene dicarboxylic acids and characterized by HR ESI-MS and multinuclear NMR spectroscopy. Every divinylphenylene diruthenium subunit is oxidized in two consecutive one-electron steps with half-wave potential splittings in the range of 250 to 330...

Read more

Project B08: Nature Photonics 2017

Sub-cycle optical phase control of nanotunnelling in the single-electron regime

The high peak electric fields provided by single-cycle light pulses can be harnessed to manipulate and control charge motion in solid-state systems, resulting in electron emission out of metals and semiconductors or high harmonics generation in dielectrics. These processes are of a non-perturbative character and require precise reproducibility of the electric-field profile.
Here, we vary the carrier-envelope phase of...

Read more

Project B02: Nano Letters 2016

Coupling of Excitons and Discrete Acoustic Phonons in Vibrationally Isolated Quantum Emitters

The photoluminescence emission by mesoscopic condensed matter is ultimately dictated by the fine-structure splitting of the fundamental exciton into optically allowed and dipole-forbidden states. In epitaxially grown semiconductor quantum dots, nonradiative equilibration between the fine-structure levels is mediated by bulk acoustic phonons, resulting in asymmetric spectral broadening of the excitonic...

Read more

Project B06 - Physical Review 2016

Long-range photon-mediated gate scheme between nuclear spin qubits in diamond

Defect centers in diamond are exceptional solid-state quantum systems that can have exceedingly long electron and nuclear spin coherence times. So far, single-qubit gates for the nitrogen nuclear spin, a two-qubit gate with a nitrogen-vacancy (NV) center electron spin, and entanglement between nearby nitrogen nuclear spins have been demonstrated.
Here, we develop a scheme to implement a universal two-qubit gate...

Read more

Project C02: Nano Letters 2016

Shot noise of 1,4-benzenedithiol single-molecule junctions

We report measurements of the shot noise on single-molecule Au–1,4-benzenedithiol–Au junctions, fabricated with the mechanically controllable break junction (MCBJ) technique at 4.2 K in a wide range of conductance values from 10–2 to 0.24 conductance quanta. We introduce a simple measurement scheme using a current amplifier and a spectrum analyzer and that does not imply special requirements regarding the electrical leads.

Read more

Project C03: Physical Review 2016

Electron and electron-hole wave functions in a driven quantum contact

We study the many-body electronic state created by a time-dependent drive of a mesoscopic contact. The many-body state is expressed manifestly in terms of single-electron and electron-hole quasiparticle excitations with the amplitudes and probabilities of creation which depend on the details of the applied voltage
We experimentally probe the time dependence of the constituent electronic states by using an analog of the optical...

Read more

Project C10: Physical Review Letters 2014

Role of entropy in domain wall motion in thermal gradients

Thermally driven domain wall (DW) motion caused solely by magnonic spin currents was forecast theoretically and has been measured recently in a magnetic insulator using magneto-optical Kerr effect microscopy. We present an analytical calculation of the DW velocity as well as the Walker breakdown within the framework of the Landau Lifshitz Bloch equation of motion
The temperature gradient leads to a torque term acting on the magnetization...

Read more