Back in the 17th century the Dutch physicist Christiaan Huygens made the observation that the oscillation of two pendulums synchronize once they get under mutual influence.
This holds for even very loose coupling, for instance, when both pendulums are mounted onto the same wall. Interestingly, a large variety of oscillating systems shows this kind of behaviour, ranging from organ pipes to lasers or electronic circuits. A team of scientists in the Laser Sepctroscopy Division of Professor Theodor W. Hänsch at the Max Planck Institute of Quantum Optics (MPQ) has now succeeded in observing this technically rather important phenomenon for a single extremely cold atom (Phys. Rev. Lett. 105, 013004, 2 July 2010). As was shown in the experiment, the forces necessary for the synchronisation of the atomic oscillation with an external radiofrequency signal were as low as 5 yoctonewton (5 x 10^-24 N). Hence, single atoms can serve as extremely sensitive detectors for very weak forces – perhaps even sensitive enough for measuring the magnetic moment of a single molecule for the first time.
The experiment starts with storing a single magnesium ion in a so-called Paul-trap. The alternating fields of the trap keep the atom at a fixed point in space, whereas the very high vacuum guarantees that the ion oscillates without perturbation. The ion is then addressed by two well tuned laser beams which make it oscillate with an amplitude of around a tenth of a millimetre. High-resolution optics and a sensitive camera make it possible to register this oscillation by the emitted stray light. In order to investigate the synchronisation of the oscillation of the optically excited atom with an external source a second alternating field is applied to an electrode nearby, and the ion oscillation is monitored with a stroboscope. Once the frequency of the external signal is close enough to the oscillation frequency of the ion its motion sychronizes with the external field.
A careful determination of the forces exerted by the applied ac-field shows that even very small excitations of only 5 yN give rise to synchronisation. Without the experimental “tricks” described above it is almost impossible to detect forces of this order. For example, a force of 5 yN would displace the ion by only around one nanometer (10^-9 metre), whereas the amplitude of the ion oscillation due to its temperature already amounts to 5000 nanometres.
The extremely high sensitivity demonstrated in this experiment offers a variety of applications. For example, it could be used to measure the magnetic field of a single molecule for testing fundamental interactions. The experiment described here is a promising step in this direction. Maximilian HerrmannOriginal publication:
Dr. Olivia Meyer-Streng | idw
Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT
Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
06.12.2016 | Power and Electrical Engineering
06.12.2016 | Earth Sciences
06.12.2016 | Physics and Astronomy