Quantum mechanical behaviour at the macroscale

Most quantum physics research to date has used particles such as atoms and electrons to observe quantum mechanical behaviour. Professor Mika Sillanpää of Aalto University is now working in the relatively new field of using supercool temperatures to observe quantum features in larger objects

When considering tiny constituents of matter, such as single atoms or molecules, the laws of physics seem to contradict common sense. Atoms or small elementary particles can properly be understood only by , which tells that matter and energy consist of small packets, quanta. On the other hand, according to quantum physics, they both can also behave as waves. Without such detailed knowledge of the fundamental laws of nature, modern electronics, for example, could not have been constructed.

Professor Mika Sillanpää of the Department of Applied Physics and O.V. Lounasmaa laboratory at Aalto University is carrying out basic research on micromechanical resonators measured at ultralow temperatures.

Since everything is built with atoms, macroscopic sized objects should, in principle, follow the counterintuitive quantum laws. Quanta are never directly observed, because the quantum waves in sizable objects usually immediately cancel each other out, leaving behind the everyday world. However, if well protected from noise of the surroundings, tangible objects can retain some quantum features. "We use quite sophisticated cryogenic equipment to cool our samples close to -273°C, known as absolute zero," Sillanpää explains. "At this temperature, the energies of single vibrational quanta are not excessively disturbed by random motion of atoms due to temperature. This allows us to observe quantum-mechanical behaviour in relatively macroscopic objects such as the micromechanical oscillators that we work with."

In Sillanpää's work, the micromechanical resonators are housed inside a superconducting cavity resonator. When the two quantum resonators are put together, they begin to exchange quanta, and their resonant motion thus becomes amplified. This is very similar to what happens in a guitar, where the string and the guitars' echo chamber resonate at the same frequency, but instead occurring in the realms of quantum physics. Instead of the musician playing with the guitar string, the energy source is provided by a microwave laser.

Quantum computing

Recently, Sillanpää's group successfully connected a superconducting quantum bit, or qubit, with a micrometre-sized drumhead and transferred information from the qubit to the resonator and back again. "This work represents the first step towards creating exotic mechanical quantum states," he states. "For example, the transfer makes it possible to create a state in which the resonator simultaneously vibrates and doesn't vibrate."

A qubit is the quantum-mechanical equivalent of the bits used in computers. A traditional bit can be in a state of 0 or 1, whereas a qubit can be in both states at the same time. In theory, this situation allows for a quantum calculation in which the operations are performed simultaneously for many possible computational pathways. In the case of a single qubit, this means zero and one, but as the number of qubits increases, the amount of possible numbers and simultaneous calculations grows exponentially. The quantum state of a qubit is very fragile and easily disturbed between and during the operations. The key to successful quantum calculation is being able to protect the qubit state from disturbances in the environment.

Although Sillanpää's ERC project is basic research aimed at understanding the laws of nature, there is a technological motivation in the distance: future quantum information processing. Micromechanical resonators can serve as an intermediator of quantum information from the quantum bits via optical fibers even to the other side of the Earth, which could form the basis of a internet.

Explore further

Combining quantum information communication and storage

Provided by Insight Publishers
Citation: Quantum mechanical behaviour at the macroscale (2015, February 6) retrieved 17 September 2019 from https://phys.org/news/2015-02-quantum-mechanical-behaviour-macroscale.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Feb 06, 2015
Typical nonsense.

Vibrate and not vibrate at the same time?

Wow. this stupidity knows no bound.

Is this some propaganda the U.S. and Europe feed to the Russians and Chines in order to try to confuse them about science?

How do you make truth table out of something which is allegedly on and off simultaneously?

I think this is just another example of people misunderstanding reality completely in mainstream physics.

You can't design a logic gate that makes a decision based on information that can be both true and false at the same time, because it produces indeterminant outcomes.

Feb 06, 2015
Humbled, quantum mechanics is the correct way of describing nature. Quantum effects can be readily observed in in things like the behavior of super fluids and super conductors, which can only be explained by quantum mechanics. There's a million other things, as well such as photoelectric effect. We look at the world this way for a reason.

Feb 06, 2015
"because it produces indeterminant outcomes." What's wrong with that? Zero is indeterminate in a trinary state

Feb 07, 2015
This comment has been removed by a moderator.

Feb 07, 2015
"because it produces indeterminant outcomes." What's wrong with that? Zero is indeterminate in a trinary state

Cosmology for one.

All of astronomy and cosmology is based on the assumption of continuous reality with some form of traceable determinism.

If outcomes are indeterminate then looking into deep space to study the "past" is a complete waste of time, since the "reality" of the "past" of what "was" out there is actually changing, and not just it's "present" or "future".

Logic needs to be fully reversible for science to work in reality, and especially for computers to work with operations in applications. If an operation produces a condition that is both 0 and 1 then it is not fully reversible and that produces problems. Cryptography must be fully reversible for example, or it's useless.

Cosmology operates under the assumption that logic is fully reversible. If quantum outcomes are indeterminate then cosmology is a faulty science.

Feb 08, 2015
QM appears contradictory because we live in momentum space which is pointlike, but construct our perceptions in intervals like space and time which always require two measurements. Together they form a vortex triad of "classical" opposites in spacetime and an unpredictable "order from chaos" gestalt in a particlelike momentum phase space

Unfortunately lovers of spacetime must suffer the fact that casality is different or even opposite in different inertial frames of reference, but also different observers have different SPACETIMES. Thus two observers cannot generally agree upon an object being in the same space or the same time for longer durations of either

The mystery is what shapes momentum space

Feb 08, 2015
The Kabbalah suggests that reality is a series of nested paradoxes composed of opposites, into which one must grasp the hidden nature of the schism thereby eliminating the opposites and making reality again whole. The theme is ubiquitous also in religions such as Buddhism. I don't advocate religion but I suggest this ancient wisdom as intellectual scaffolding worth of more investigation

Feb 09, 2015
This comment has been removed by a moderator.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more