Press Releases

Breaking Newton's Law

In the quantum world, our intuition for moving objects is strongly challenged and may sometimes even completely fail. An international team of physicists of the Universities of Innsbruck, Paris-Sud and Harvard as well as the Technical University of Munich (TUM) has found a quantum particle which shows an intriguing oscillatory back-and-forth motion in a one-dimensional atomic gas instead of moving uniformly.

 

A ripe apple falling from a tree has inspired Sir Isaac Newton to formulate a theory that describes the motion of objects subject to a force. Newton’s equations of motion tell us that a moving body keeps on moving on a straight line unless any disturbing force may change its path.

The impact of Newton’s laws is ubiquitous in our everyday experience, ranging from a skydiver falling in the earth’s gravitational field, over the inertia one feels in an accelerating airplane, to the earth orbiting around the sun.

In the quantum world, however, our intuition for the motion of objects is strongly challenged and may sometimes even completely fail. In the current issue of “Science” an international team of physicists from Innsbruck, Munich, Paris and Cambridge (USA) describes a quantum particle that shows a completely unexpected behavior.

In a quantum gas the particle does not move like the famous falling apple, but it oscillates. At the heart of this surprising behavior is what physicists call ‘quantum interference’, the fact that quantum mechanics allows particles to behave like waves, which can add up or cancel each other.

Approaching absolute zero temperature

To observe the quantum particle oscillating back and forth the team had to cool a gas of Cesium atoms just above absolute zero temperature and to confine it to an arrangement of very thin “tubes” realized by high-power laser beams. With a special trick, the atoms were made to interact strongly with each other.

At such extreme conditions the atoms form a quantum fluid whose motion is restricted to the direction of the tubes. The physicists then accelerated an impurity atom, which is an atom in a different spin state, through the gas. In our everyday world this corresponds to the apple falling from the tree.

The scientists, however, observed that the quantum wave of the atom was scattered by the other atoms and reflected back again. The result is a striking oscillatory movement. The experiment demonstrates that Newton’s laws cannot be used in the quantum realm.

Quantum fluids sometimes act like crystals

The fact that a quantum-wave may get reflected into certain directions has been known since the early days of the development of the theory of quantum mechanics. For example, electrons reflect at the regular pattern of solid crystals, such as a piece of metal. This effect is termed “Bragg-scattering”.

However, the surprise in the experiment performed in Innsbruck was that no such crystal was present for the impurity to reflect off. Instead, it was the gas of atoms itself that provided a type of hidden order in its arrangement, a property that physicist dub “correlations”.

The publication has demonstrated how these correlations in combination with the wave-nature of matter determine the motion of particles in the quantum world and lead to novel and exciting phenomena that counteract the experiences from our daily life.

Understanding fundamental processes in electronics components

“Understanding the oddity of quantum mechanics is also relevant in a broader scope,” says Michael Knap, Professor for Collective Quantum Dynamics at the Technical University of Munich. “It might help to understand and optimize fundamental processes in electronics components, or even transport processes in complex biological systems.”

 

Publication

Bloch oscillations in the absence of a lattice

Florian Meinert, Michael Knap, Emil Kirilov, Katharina Jag-Lauber, Mikhail B. Zvonarev, Eugene Demler, Hanns-Christoph Nägerl

DOI: 10.1126/science.aah6616

 

Contact

Prof. Dr. Michael Knap

 


For original press release, please visit here

Shaken, but not stirred

When James Bond asks the barkeeper for a Martini, “shaken, not stirred”, he takes it for granted that the ingredients of the drink are miscible. In the quantum world, however, he might be in for a surprise! A team of physicists from the Technical University of Munich (TUM), the Ludwig-Maximilians-University Munich (LMU) and the Max Planck Institute for Quantum Optics (MPQ) has now prepared a form of quantum matter that is robust to shaking – a property that would make life difficult for cocktail lovers.

 

A team of physicists have created a quantum system with unusual stability

A team of physicists have created a quantum system with unusual stability. – Image: Christoph Hohmann / NIM

In fact, the problem with quantum matter normally lies in its extreme sensitivity to perturbation: The action of even weak oscillatory forces typically has drastic consequences in the long term and is expected to dramatically alter its initial state. Therefore – up until now – it had been widely assumed that quantum systems should normally be susceptible to mixing, since shaking injects energy into the system, and should cause it to heat up indefinitely.

Now the research groups from Munich have experimentally characterized an exotic quantum state that does not behave this way: When subjected to a periodic force, its constituents do not mix.

They first cooled a cloud of potassium atoms to an extremely low temperature in a vacuum chamber. They then loaded the ultracold atoms into an optical lattice formed by counter-propagating laser beams that generate standing waves. Such a lattice can be thought of as a network of energy wells in which the atoms can be individually trapped, like the eggs in an egg carton.

Controlled disorder

“In addition, we were able to introduce disorder into the lattice in a controlled manner by randomly altering the depth of the individual wells,” says Pranjal Bordia, first author of the study. By this means, the potassium atoms could be localized in special areas of the network, and were not evenly distributed within the lattice.

The physicists then shook the lattice by periodically varying the intensity of the laser light. But the system turned out to be so stable that the localized groups of atoms did not mix. The potassium atoms were tossed about somewhat, but their overall distribution in the lattice remained intact.

Confirmation of the theory

The experiments confirm recently published predictions relating to a specific class of quantum systems in which disorder actually serves to localize quantum particles. Moreover, the observation that this newly realized exotic quantum state remained stable for an unexpectedly long time is supported by the results of subsequent high-performance numerical simulations carried out by Michael Knap, Rudolf Mößbauer Tenure Track Professor for Collective Quantum Dynamics at the Physics Department of Technical University of Munich.

The experimental demonstration of this quantum system could have practical consequences for efforts to develop robust quantum computers, and studies of exotic quantum states promise to yield new insights into fundamental issues in theoretical physics.

The work was funded by the European Union (FP7, UQUAM, AQuS), by the German Research Foundation via the TUM Institute for Advanced Study and the Cluster of Excellence Nanosystems Initiative Munich (NIM).

 

Publication

Periodically Driving a Many-Body Localized Quantum System

Pranjal Bordia, Henrik Lüschen, Ulrich Schneider, Michael Knap, and Immanuel Bloch
DOI: 10.1038/nphys4020

 

Contact

Prof. Dr. Immanuel Bloch

Prof. Dr. Michael Knap

 

TUM press release (English)/ LMU press release (German)

 

 

 

Spanish Cellex Foundation endows ICFO-MPQ Research Fellows


On 26 February 2015, a new collaboration agreement between ICFO (The Institute of Photonic Sciences in Spain) and the Max Planck Institute of Quantum Optics was signed which facilitates cooperation on topics of common interests between both institutes.


ICFO- The Institute of Photonic Sciences conducts wide scope research on optical and photonic sciences, with particular interest in quantum optics, quantum information, nano-optics and atto-optics. It was founded 12 years ago by the Government of Catalonia and has already demonstrated its relevance and position in the international scientific community. Prof. Ignacio Cirac, Director at the Max Planck Institute of Quantum Optics and head of its Theory Division, has collaborated with ICFO for many years and sits on the institute’s Scientific Advisory Board. “We have long awaited the opportunity to build a formal bridge between MPQ and ICFO, and thanks to the support from Fundació Privada Cellex, we will be able to address some important fundamental questions in quantum and atto-optics that will be incredibly enriching for the field”, the Spanish physicist points out.

Fundació Privada Cellex is a non-profit private foundation devoted to the advancement of science and education for the benefit of humankind. It supports students, researchers and research institutions, primarily those based in Catalonia, through scholarships and grants. The private foundation that has been established by Dr. Pere Mir i Puig, has a long tradition in promoting research in medicine, physics, mathematics and education. Cellex now agrees to fully finance this new program between ICFO and MPQ for the duration of six years, creating four postdoctoral positions who will jointly work at ICFO and MPQ as “Cellex ICFO-MPQ Research Fellows”. The institutes will have the freedom to define cutting edge research projects between at least one ICFO research group and one MPQ research division.

Photo: Signing the agreement, from left to right: Dr. Pere Mir i Puig, Fundació Privada Cellex, Hon. Andreu Mas Colell, Government of Catalonia and Chairman of ICFO’s Board of Trustees, and Prof. Dr. Ignacio Cirac
Photo credit: ICFO|RJosa

By Olivia Meyer-Streng

Original source [here]

"Science Through Symmetry" Report at International Innovation

Jan Von Delft writes about quantum physics: "Quantum Mechanics the field of physics that deals with interactions on the smallest scale known to man – which is very small indeed. For example, the action of lifting a 1 kg weight one metre off the ground would cost around 10 joules of energy; quantum mechanics works in terms of Planck’s constant, the smallest measurable unit of action, which is roughly 6.626 x 10-34 Js-1. Because of this incomprehensible difference in scale, the laws of physics also differ; uncertainty plays a significant role in quantum interactions, and the distinction between matter and waves is no longer clear. When scientists attempt to study quantum mechanics, therefore, calculations of vast complexity are required".

A partnership of researchers based at Ludwig Maximilian University of Munich, Germany, is combining computational physics and nontrivial mathematics to solve some of quantum physics’ most challenging models. The co-principal investigator of this project is nanophysicist Professor Jan von Delft, who shares details of his career in quantum nanoscience, and the computational cost-saving approaches he has helped devise in this important area. Other key team members are Dr. Andreas Weichselbaum and Prof. Ulrich Schollwöck.

Original Source: International Innovation

Usa-News interview with Gerhard Rempe

Gerhard Rempe, Director at the Max Planck Institute of Quantum Optics in Garching, and his colleagues investigate the fundamentals of quantum facts technology.The researchers have learned to manage individual atoms and photons, or light particles, and the interactions in between the two in a incredibly precise way.

When describing the problems that he an his team had to overcome when manipulating atoms and photons, Gerhard Rempe remarks "Cautious: the atoms may be exceptionally compact, but our photons absolutely are not. They extend more than various hundred metres, but move really quick, of course. Simply because they extend more than such a huge space, we can choose their frequency, meaning their colour, with extreme precision."

Original source: Dailynewsen.

Interview with Ignacio Cirac in Methode Magazine

On research: "[...] However, there is another type of research that is carried out on the long-term. This type of research does not seek to develop any particular product, but intends to achieve bigger goals that can transform the world of technology. This is what many physicists and scientists do and what research in quantum computing is about. Quantum computing does not intend to build a quantum computer but to develop a kind of technology that affects not only computers, but also communication systems and other things we can’t even start to imagine."

Original source: Methode Magazine, University of Valencia.

Interview with Immanuel Bloch in Research Media Ltd

From quantum computing to electron dynamics, Professor Dr Immanuel Bloch reveals the cutting-edge work taking place within each of the Institute’s five divisions, and examines the questions raised by the controversial and unexpected findings of a breakthrough technique.

Original source: Research Media Ltd.

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