User:Bob K31416/SC/sandbox

http://www.ensmp.fr/aflb/AFLB-311/aflb311m387.pdf

2 Materials and Methods
A schematic representation of our apparatus is shown in Fig. 2. We used an electronic timer and Geiger counter to detect alpha particle released from a small sample of radium over a 0.19 second window. A decay event within the measuring window released the hammer in the chamber labelled “decay”, whereas the absence of a decay event released the hammer in the “nodecay” chamber. A separate reset circuit released the unfallen hammer, if desired, thereby destroying the information about the decay event encoded by the hammers. The release of a hammer caused a ball to drop into an output box: if a decay event occurred, this was the ball loaded into the hole labelled “true”, otherwise the ball loaded into the hole labelled “false”.

Figure 2. A schematic representation of the experimental box, as viewed from the side (upper panel) and from above (lower panel). A decay-event within the timed window triggered the solenoid D, releasing hammer A. In turn, this removed a baffle (E) and allowed a ball, previously loaded through hole G, to roll into the output box (F). Conversely, if no decay-event occurred within the timed window, solenoid C was triggered, releasing hammer B and allowing a ball, previously loaded through hole G’, to roll into the output box. Hole G was labelled “True”, indicating that if a ball labelled “decay” was loaded in this hole, it would appear in the output box if a decay event occurred. Conversely, hole G’ was labelled “False”. The box was opaque, but had a hinged lid to allow observation of the state of the hammers.

We shielded the Geiger counter and radium sample with lead to ensure that an average of 84% of decay events resulted from the radium sample, rather than from background radiation, and that the probability of a decay event occurring in the 0.19 second recording window was 0.5 (Fig. 3). The Geiger counter was a Brown 150 (Mini-instruments, London), and the radium sample was the luminous face of a small clock. The electronic timer was a custom-built circuit, which was remotely triggered by a switch mounted in a different room. A reset switch, which released both hammers, was similarly remotely mounted.

To determine how to load balls into the box, we used “truth-cards” that were printed by a computer using a random number generator [12] seeded from the computer’s clock. In the main experiment, Observer B remained in an isolated waiting room (waiting room B) whilst Observer A loaded a ball labelled “decay” into either the “true” or “false” hole, depending upon a printed truth-card withdrawn from a sealed envelope, and loaded an unlabelled ball into the remaining hole. Observer A then exited the laboratory to a separate isolated waiting room (waiting room A), and remotely triggered the timed recording by the Geiger counter. After the recording, Observer B entered the laboratory and retrieved the ball from the output box. At this point in the experiment, the true nature of the quantum event is not known by either observer, and can only be determined by a combination of the information known to Observer A and Observer B, as outlined in the truthtable in Fig. 1. Observer A then returned to the laboratory and, whilst observing his truth-card, asked Observer B to report which ball he was holding and looking at. It was only at this point that the information from Observer A and Observer B was combined, and that Observer A became conscious of the quantum state. Any change in the state of the truth-card (from “true” to “false”, or vice versa) or the ball (from labelled “decay” to unlabelled, or vice versa) was recorded. Observer B then opened the box, and compared the state of the hammers with the state predicted from the truth-card/ ball combination. We performed the experiment nine times, giving a probability of >0.99 that at least one repetition contained a decay event resulting from the radium source, rather than background radiation. We then repeated the experiment with the roles of Observer A and Observer B reversed. For all experiments, we used a continuous background of auditory noise that masked any sounds emanating from the box. We checked for any procedural errors (e.g. mis-loading of the box) by reviewing a videotape-recording of events at the conclusion of the experiment.


 * In a box, Geiger counter detected alpha particle from nuclear decay. Also in box were two hammers. Two human observers A and B outside of box.
 * Observer A received a sealed envelope containing a card with either "true" or "false".
 * Observer B out of lab. Observer A opened envelope and loaded a ball labeled "decay" into either true hole or false hole according to card and loaded the unlabeled ball into the other hole.
 * if alpha detected during 0.19s then "decay" hammer (DH) released and a ball loaded into "true" hole was released to go outside box. Otherwise "nodecay" hammer (NH) released and a ball loaded into "false" hole was released to go outside box.
 * Outside the lab Observer A privately triggered the beginning of the 0.19 s period of time in which one of the hammers and its ball were released.
 * Observer B retrieved the released ball in lab.
 * Observer A entered the lab to join Observer B.
 * Observer A looked at his card, as a reminder, while Observer B disclosed what ball was retrieved, "decay" or unlabeled.
 * Observer A is now conscious of the quantum state of the system in the box, i.e aware of which hammer was released, DH or NH, since he knows which balls were loaded into each hole and which ball came out of the box. For example, if "decay" ball loaded into "false" hole and Observer B retrieved "decay" ball, then "no decay" hammer was previously released.
 * After becoming conscious of the result, Observer A looked at and recorded any change in the state of the truth-card (from “true” to “false”, or vice versa) or the ball (from labelled “decay” to unlabelled, or vice versa). (But if the card and ball could change, why couldn't Observer A's memory and any notes taken change too, so that Observer A couldn't tell if the card and ball changed?)
 * Observer B then opened the box, and compared the state of the hammers with the state predicted from the truth-card/ball combination.

3 Results and Discussion
In all repetitions, we found that neither the state of the ball nor the state of the truth-card changed upon Observer A becoming conscious of the true output of the Geiger counter. In addition, the state indicated by the ball/ truth-card combination always agreed with the state of the hammers within the box. Our results imply that an observer does not need to be conscious of the outcome of a quantum detection event in order for a quantum wavefunction to collapse.

A potential objection to the above experiment is that the state of the ball, and hence Observer B’s perception of the state of the ball, may exist as a superposition until such time as Observer A becomes conscious of the measurement result. Therefore, we designed an extra experiment to investigate this possibility. The experiment proceeded as described previously, save for the following changes. Observer A loaded only the ball labelled “decay” into the box, using either the “true” or “false” hole as determined by a coin toss (“true” = heads). Meanwhile, in waiting room B, Observer B performed a coin-toss to decide which state (heads or tails) would be used to represent whether a ball was present in the output box. It should be noted that such coin-tosses, although chaotic, are not quantum events and so have outcomes that are fixed. Observer B, after noting the presence or absence of a ball in the output box but not removing the ball, then remotely triggered the reset circuit. This circuit destroyed the information encoded by the hammers in the box, thereby leaving the combined information possessed by the two observers as the only way of determining the quantum state. No videotape recording was made of the experiment. Observer B never revealed the outcome of his coin-toss to Observer A, however, thus if a superposition existed regarding the potential state of the ball it remained permanently uncollapsed. ***** Such a superposition can be allowed to escape the confines of our laboratory by telling the reader that the state of the output box in the experiment was “heads”. Therefore, all readers of this article are now part of any superposition lingering in the experiment.

The fact that we can state a definite outcome, albeit coded, from the experiment is inconsistent with the presence of an uncollapsed superposition, however. Therefore, any explanation of our main experiment that requires a superposition involving both the boxed-system and one or more of the observers can be discounted. Our results are consistent with the idea that a measurement from the Geiger counter is sufficient to collapse the quantum state, most likely because the counter involves amplification processes that are irreversible [13]. Conscious perception of the outcome of a quantum measurement is not a prerequisite for the collapse of a quantum wavefunction.


 * state of ball and card did not change when Observer A became conscious of Geiger counter output
 * state indicated by ball/card combination always agreed with state of hammers
 * implies an observer does not need to be conscious of the outcome of a quantum detection event in order for a quantum wavefunction to collapse.
 * but state of the ball, and hence Observer B’s perception of the state of the ball, may exist as a superposition until such time as Observer A becomes conscious of Geiger counter output
 * additional experiment, same as previous, except:
 * Observer A loaded only one ball, "decay", using a coin toss to determine which hole
 * "Observer B performed a coin-toss to decide which state (heads or tails) would be used to represent whether a ball was present in the output box." (e.g. if coin toss was heads, then if a ball was present in the output box, Observer B would record "heads". If coin toss tails, then ball in box results in "tails" being recorded.) Observer B never revealed the outcome of his coin toss to Observer A.
 * Observer B noted the presence or absence of a ball in the output box, i.e. recorded "heads" or "tails", then triggered reset (both hammers down and ball would go into output box if it already wasn't there)
 * Observer B triggered "reset" and never revealed to Observer A whether "heads" or "tails" denoted the presence of a ball in the output box. Thus, if a superposition existed regarding the potential state of the ball, it remained permanently uncollapsed since the information of the two observers  would not be combined to determine the state of the ball before the reset. "Potential state of the ball" means what the presence or absence of the ball, before reset, indicated regarding which hammer was released.
 * The state of the ball in the experiment was “heads”. (Note that we don't know whether or not this means that there was a ball in the box because we don't know the result of Observer B's coin toss, which determined whether "heads" or "tails" indicated a ball in the box.)