realworld quantum effects

i’m trying to picture what this would look like, when quantum processes in the game / players produce quantum effects in the real world.

researchers reported finding telltale signs of a link between quantum effects and thermodynamic properties in the “heavy fermion” compound YbRh2Si2 (YRS) containing the elements ytterbium, rhodium and silicon. This material contains a quantum critical point that separates a magnetic phase from a non-magnetic one

Phase transitions, such as water vaporizing or melting, typically occur as a result of temperature change. Quantum phase transitions, by contrast, arise when the forces of quantum mechanics drive a macroscopic material from one type of order to another. A quantum critical point describes the material at the cusp of such a transition.

A quantum critical point occurs at the absolute zero of temperature, which cannot be reached experimentally. However, the effects of quantum phase transitions can be seen in the laboratory at sufficiently low temperatures. In the case at hand, a group of experimentalists at the Max Planck Institute of Chemical Physics of Solids in Dresden made exquisite measurements at very low temperatures of the properties of the metallic YRS that show a quantum phase transition between a magnetic and a non-magnetic state.

Usually, phase transitions are governed by the behavior of a macroscopic variable, the order parameter. In the case of the liquid to vapor transition mentioned above, the density is the order parameter. For a quantum phase transition, an energy scale describes the energy cost to nucleate a domain with a finite order parameter in the state without that order. This energy scale, believed to be the only relevant one by conventional wisdom, describes the fluctuations of the order parameter. The paper reports the measurements of two thermodynamic properties — magnetization and magnetostriction, or the change in volume as a function of change in magnetic field — as the material was cooled to near absolute zero.

“Our measurements revealed that a second thermodynamic energy scale exists in the YRS compound,” said Philipp Gegenwart. “This additional energy scale goes beyond the theory based on fluctuations of the order parameter.”

One possible explanation for this additional energy scale invokes the destruction of a quantum effect, called entanglement, at the quantum critical point. Another ascribes it to the effective disintegration of an electron into separated spin and charge carrying objects, or excitations.

and

Scientists have long wanted to demonstrate superposition in larger objects but a significant challenge here is to eliminate all thermal vibrations in the object, which mask or destroy quantum effects. To achieve this, the object needs to be cooled down to its quantum ground state – at which point the amplitude of vibrations reduces to close to zero.

The object is a mechanical resonator made of aluminium and aluminium nitride, measuring about 40 µm in length and consisting of around a trillion atoms. It is a thin disc, which resonates at about six billion vibrations per second.

In the experiment, Cleland’s team reduce the amplitude of the vibrations in the resonator by cooling it down to below 0.1 K. The high frequency of the aluminium resonator was key to the experiment’s success, because the temperature to which an object needs to be cooled in order to reach its ground state is proportional to its frequency. “A regular tuning fork, for example [with significantly lower frequency], would need to be cooled by another factor of a million to reach the same state,” Cleland said.

Next, the team measured the quantum state of the resonator by connecting it electrically to a superconducting quantum bit or “qubit”. The qubit acts, in fact, like a “quantum thermometer” that can identify just one quantum thermal excitation, or phonon. Once this has been done, the qubit can then be used to excite a single phonon in the resonator. This excitation can be transferred many times between the resonator and qubit.

In this way the researchers created a superposition state of the resonator where they simultaneously had an excitation in the resonator and no excitation in the resonator, such that when they measured it, the resonator has to “choose” which state it is in. “This is analogous to Schrödinger’s cat being dead and alive at the same time,” says Cleland.

“Unlike other measuring instruments, [the qubit] allowed us to measure the mechanical resonator while preserving all quantum effects,” Cleland told physicsworld.com. “Most measuring instruments disturb the mechanical object by heating it up, and so destroy the very quantum effects being sought.”

The experiments could have important implications for new quantum technologies, like quantum information processing, and for investigating the boundaries between the quantum and classical worlds – one of the least understood areas in physics.

and about decoherence

There are two reasons why in usual materials and behaviors the underlying quantum mechanical nature is masked:

a) As you guessed the small magnitude of the numbers entering and deciding the thresholds of observation of quantum effects. These depend on the small value of h-bar, a constant which controls the scale of clear quantum behavior in interactions.

b) The second reason is coherence. A classic example of coherence/decoherence is the following: when soldiers march across an old bridge they break step. If they do not, if they keep coherently marching in step, the additive and synchronous in time vibrations induced on the bridge may destroy it by resonating with its basic resonance.

When one has a wave description, and quantum mechanics describes the probability of interactions mathematically as a wave, there are phases between waves. If the waves are in step, i.e. the phases are fixed and unchangeable, macroscopic manifestations of quantum effects can appear, as happens with superconductivity and superfluidity. Fortunately for the way we see the world usually, the smallness of h-bar assures that unless great effort is made to keep the phases, the phases are lost statistically, due to zillions of interactions at the molecular level. This is called decoherence and leads to the classical physics level we usually live with.

here are some experiments with psi effects

physiological indices of participants’ emotional arousal were monitored as participants viewed a series of pictures on a computer screen. Most of the pictures were emotionally neutral, but a highly arousing negative or erotic image was displayed on randomly selected trials. As expected, strong emotional arousal occurred when these images appeared on the screen, but the remarkable finding is that the increased arousal was observed to occur a few seconds before the picture appeared, before the computer has even selected the picture to be displayed.

There were no significant sex differences in the present experiment. Over the years, however, the trait of extraversion has been frequently reported as a correlate of psi, with extraverts achieving higher psi scores than introverts.

Eysenck attributed the positive correlation between extraversion and psi to the fact that extraverts “are more susceptible to monotony…[and] respond more favourably to novel stimuli” (1966, p. 59). Sensation seeking is one of the 6 facets of extraversion on the Revised NEO Personality Inventory

In the experiment just reported, for example, there are several possible interpretations of the significant correspondence between the participants’ left/right responses and the computer’s left/right placements of the erotic target pictures:
1. Precognition or retroactive influence: The participant is, in fact, accessing information yet to be determined in the future, implying that the direction of the causal arrow has been reversed.
2. Clairvoyance/remote viewing: The participant is accessing already-determined information in real time, information that is stored in the computer.
3. Psychokinesis: The participant is actually influencing the RNG’s placements of the targets.
4. Artifactual correlation: The output from the RNG is inadequately randomized, containing patterns that fortuitously match participants’ response biases. This produces a spurious correlation between the participant’s guesses and the computer’s placements of the target picture.

the correlation between stimulus seeking and psi performance was .17 (p = .02). Table 3 reveals that the subsample of high stimulus seekers achieved an effect size more than twice as large as that of the full sample. In contrast, the hit rate of low stimulus seekers did not depart significantly from  chance:

Those who follow contemporary developments in modern physics, however, will be aware that several features of quantum phenomena are themselves incompatible with our everyday conception of physical reality. Many psi researchers see sufficiently compelling parallels between these phenomena and characteristics of psi to warrant considering them as potential candidates for theories of psi. (For a review of theories of psi, see Broderick, 2007, and Radin, 2006.)

The development in quantum mechanics that has created the most excitement and discussion among physicists, philosophers, and psi researchers is the empirical confirmation of Bell’s theorem (Cushing & McMullin, 1989; Herbert, 1987; Radin, 2006), which implies that any realist model of physical reality that is compatible with quantum mechanics must be nonlocal: It must allow for the possibility that particles that have once interacted can become entangled so that even when they are later separated by arbitrarily large distances, an observation made on one of the particles will be correlated with what will be observed on its entangled partners in ways that are incompatible with any physically permissible causal mechanism (such as a signal transmitted between them). The most extensive discussion of how entanglement might provide a theory for psi will be found in Radin’s (2006) Entangled Minds: Extrasensory Experiences in a Quantum Reality. Radin argued that over the past century, most of the fundamental assumptions about the fabric of physical reality have been revised in the direction predicted by genuine psi. This is why I propose that psi is the human experience of the entangled universe. Quantum entanglement as presently understood in elementary atomic systems is, by itself, insufficient to explain psi. But the ontological parallels implied by entanglement and psi are so compelling that I believe they’d be foolish to ignore (p. 235).

Bell’s theorem highlights a second prominent feature of quantum theory: the role that the act of observation plays in determining what will be observed. For example, the  common-sense assumption that dynamic properties of a particle (e. g., its position and momentum) have definite values before they are actually observed is falsified by the empirical confirmation of Bell’s theorem. Instead, the values of such properties remain only probabilities until the act of observation “collapses the quantum wavefunction” and causes the properties to acquire definite values. Even before Bell’s theorem, it was known that whether light behaves like waves or like particles depends on the conditions of observation. These features of quantum mechanics have led to “observational” theories of psi in which it is not just the act of observation but the consciousness of the human observer that plays an active role in what will be observed (Radin, 2006, pp 251–252). As Radin acknowledges in the paragraph quoted above, quantum entanglement does not yet provide an explanatory model of psi. More generally, quantum theories of psi currently serve more as metaphors than models, and some psi researchers with backgrounds in physics are even more skeptical: “I don’t think quantum mechanics will have anything to do with the final understanding of psi” (Edwin May, quoted in Broderick, 2007, p. 257).

Advertisements

About jeanne

artist, grandma, alien

Posted on January 9, 2012, in quantum, research. Bookmark the permalink. Leave a comment.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: