As technology advances, we must reconsider previous methods of reasoning. In the past, we reasoned that every basketball win we had was due to skill – that still holds. Every loss, however, can be reasoned using quantum teleportation – and considering the complexity of the concept, it would be a very useful argument to suggest to the unknowing few who dare to bash Duke basketball. How else could we explain our low free throw percentage in the recent games, if the ball did not teleport outside of the hoop? As absurd as it seems – indeed, this explanation would’ve been laughed at a decade ago – we now know that teleportation is not just science fiction; in fact, quantum teleportation has earned its place in major scientific books and journals and is under serious consideration, due to reasons described later in this article.

Quantum teleportation is a term used to describe the transfer of a particle state from one particle to another (Bouwmeester et al., 1997), which differs from cloning (Ball, 2002) in that the particle is not duplicated but the properties of the particle is cut and pasted.  The concept and theory behind teleportation was suggested by Bennett et. al. in 1993 (Bennett et al., 1993), but verification of the theory only came in 1997. Bouwmeester et. al. (Bouwmeester et al., 1997) successfully teleported single photons in 1997, raising the question: could the same be done with matter, and a more important question: could the same be done with a basketball? If so, what are its limitations and its implications? To answer these questions, the crux of quantum teleportation and perhaps one of the most interesting topics of quantum mechanics – entanglement – needs to be considered, followed by a description of how particles could be teleported.

Entanglement is a property that entangled particles share. Entangled particles are particles that share the same quantum state, such that a measurement of the state of one of the particles will affect the state of the other entangled particle in a predictable manner. “Measurement” refers to any interaction with the environment. Entanglement could be more easily understood by using an analogy, and the following is a modification of the story of Schroedinger’s cat. Imagine encasing two people in an enclosed room; for convenience, lets name them Reggie and Spike. A sound sensor activates if Reggie and Spike start an argument, which prompts the release of a sleep-inducing agent. Unless the room is opened, it is impossible to determine the state of the Reggie and Spike- whether they are sleeping or awake. Hence, the state of Reggie and Spike could be described as both sleeping and awake if measurements are not taken. By taking a measurement, the state of the Reggie and Spike is forced to assume one of these possible states. This reasoning is termed the “projection postulate”. If they are asleep at the time of the measurement, then it could be concluded that the sound sensor activated during the time period of the experiment. The state of Reggie and Spike and the state of the sound sensor  (whether it has been activated or not) are linked. The link between particles in a similar manner is called entanglement.

To establish this link, Bouwmeester’s et al (Bouwmeester et al., 1997) split photons in a crystal (in a process called parametric down-conversion) to give entangled photons. By separating these entangled photons to the source and destination of teleportation, performing another entanglement with the photon at the source (which is entangled with the photon at the destination) with the photon to be teleported, taking a measurement of these photons at the source and performing a suitable transformation on the entangled photon at the destination based on these measurements, the desired photon could be teleported. This process was conducted by Bouwmeester, and indeed photons of various polarizations were teleported successfully.

Bouwmeester’s experiment provides substantial framework to further studies on quantum communication (Marcikic, Riedmatten, Tittel, Zbinden, & Gisin, 2003), quantum computers (Chuang, Vandersypen, Zhou, Leung, & Lloyd, 1998; Gottesman & Chuang, 1999), and quantum encryption (Hillery, 2003). The fact that two states could be stored in one entangled particle suggests the memory potential of each particle is doubled. With higher levels of entanglement, more memory could be packed per particle, giving incredible computing potential.

Although the potential in this field is large, and teleportation of photons has been observed, it is not likely for practical macroscale teleportation to take place in the near future. Entangled particles are not produced efficiently through the methods used for generating them - “less than one in ten billion” photons produce entangled pairs (Entanglement enhanced, 2001) during spontaneous parametric down-conversion – making the teleportation process rather inefficient. More importantly, it is difficult to teleport matter – a collection of atoms – since any interaction between these atoms would mean that a “measurement” is made, leading to unwanted state changes prior to teleportation. Recently, two clouds containing 10¹² atoms each have been successfully entangled for more than 0.5ms (Brian Julsgaard, 2001), but this amount of time is too small to separate the entangled particles (let alone taking measurements and conducting transformations) to perform a meaningful teleportation. Much work is needed until complex structures of different atoms could be teleported.

So how did we lose to Maryland? Maybe they didn’t use teleportation. Given the technology at hand, they probably won God’s sympathy after all.

           

 

References

 

Ball, P. (2002). Physics bans cloning. Retrieved February 18th, 2003, from http://www.nature.com/nsu/020520/020520-1.html

Bennett, C. H., Brassard, G., Crépeau, C., Jozsa, R., Peres, A., & Wootters, W. K. (1993). Teleporting an unknown quantum state via dual classical and Einstein-Podolsky-Rosen channels. Phys. Rev. Lett., 70, 1895–1899.

Bouwmeester, D., Pan, J., Mattle, K., Eibl, M., Weinfurter, H., & Zeilinger, A. (1997). Experimental Quantum teleportation. Nature, 390, 575-579.

Brian Julsgaard, A. K., Eugene S. Polzik. (2001). Experimental long-lived entanglement of two macroscopic objects. Nature, 413, 400 - 403.

Chuang, I. L., Vandersypen, L. M. K., Zhou, X., Leung, D. W., & Lloyd, S. (1998). Experimental realization of a quantum algorithm. Nature, 393, 143-146.

Entanglement enhanced. (2001, 2001). Retrieved February 18th, 2003, from http://www.nature.com/physics/physics.taf?file=/physics/highlights/6850-1.html

Gottesman, D., & Chuang, I. L. (1999). Demonstrating the viability of universal quantum computation using teleportation and single-qubit operations. Nature, 402, 390 - 393.

Hillery, M. (2003). Quantum cryptography: Code-breakers confounded. Nature, 421, 224 - 225.

Marcikic, I., Riedmatten, H. D., Tittel, W., Zbinden, H., & Gisin, N. (2003). Long-distance teleportation of qubits at telecommunication wavelengths. Nature, 421, 509-513.