Since he started studying Physics Science at the University of Concepción, Tomás Ramos had clear that his goal was to travel and specializeabroad. After he finished his master degree, and with the support of CEFOP’s professors, Tomás travelled to Austria to start his PhD at the University of Innsbruck in the research group of Dr. Peter Zoller. Only a year and a half later, his first collaboration has been accepted by the prestigious journal Physical Review Letters.
The work is an area called Quantum Optomechanics, where the main systems of study are small cavities able to localize light within them and whose walls make mechanical oscillations, in response to the radiation pressure exerted by the light. Thus, in these devices, it’s possible to couple coherently an optical mode with a mechanical mode, each of them isolated with high accuracy from its environment. Due to these features, the first application of these systems was to build high precision displacement meters, for example, for detectors of gravitational waves.
Recently, using cryogenic techniques and cooling with laser light, it was possible to bring the mechanical oscillator to the quantum regime, which means, making the motion of this almost macroscopic object to be governed by the laws of Quantum Mechanics. This quantum oscillator doesn’t stay completely still because of the quantum fluctuations, and his motion, unlike a simple classical pendulum, must always be described by an energy of integer multiples of its frequency. Each of these multiples represents a “quantum” of the energy that the oscillator has, which in the case of mechanical motion are called “phonons”, in the same way that “photons” are the elementary excitations of light.
Could you summarize what is your last published work about?
“The novelty of our work was that we realized that inside the same material from which these micro or nanoscale oscillators are made, usually of silica or silicon, defects or “impurities”are found naturally in its structure. This means, they are not perfect crystals. Surprisingly, these impurities, of which one might think are detrimental for the operation of the oscillator, actually they can be coupled individually, coherently and strongly to the mechanical oscillator, so that it begins to behave in a nonlinear way. This additional nonlinearity in the oscillator provides a way to accurately manipulate the quantum state of the oscillator, so that one can later transfer its phonons to photons of light and vice versa. In this way a realistic system for processing quantum information is provided”.
In a conventional device such as a CD, the information is stored by encoding it in a string of zeros and ones. Quantum Information, explains Tomás, replaces this classical way of storage by quantum states, which have the possibility to be in a quantum superposition of a zero and a one at the same time. A lot of these ideas form the basis of Cavity Quantum Electrodynamics, by whose progress last year Frenchman Serge Haroche won the Nobel Prize in Physics. “Our work proposes a new system, very realistic, where these ideas can be materialized, having the additional versatility to be connected to photons for transfering information over long distances, as well as to solid state devices for electronic processing, for example”, said Tomás.
Another use of these optomechanical systems coupled to this new nonlinearity, is that it’s possible to prepare the mechanical oscillator in quantum superposition states. “This means it will be possible to observe the motion of an object relatively large (much larger than an atom or molecule at least), being in two or more states simultaneously, like the famous example of Schrödinger’s cat, where the poor cat can be alive and dead at the same time, contradicting our basic notions of everyday life”.
Which is the scope of the research you are doing?
“Well, “the dream”and ultimate goal of all these efforts is to find a system highly controllable and very isolated from its environment, so that it has very little dissipation and thus one can use it to write, store, read, transmit and operate efficiently with quantum information. This hypothetical “quantum computer” would open the door to create radically new technologies in the future, since it would help us to accomplish tasks and solve problems that even with the best conceivable classical computer is not possible to solve. “
How will you continue your research?
“All this is very ambitious and mostly serves as motivation to make small steps towards that goal. Along the way, you understand deeper and deeper the principles of Atomic Physics and the Quantum Theory of Light, which can lead to the discovery of new interesting phenomena and the development of future technologies, as already we were the laser, optical fibers, photonic crystals, atomic clocks, liquid crystal displays, etc… My next project, which we are just starting, consists in studying how to include controlled dissipation in long coherence quantum systems, so that one can make use of the dissipation in a positive way when it is convenient and “turn it off” when it not needed”.
To know more about Tomás’ publication, please visit this link to the journal.