Experimental quantum teleportation. Dirk Bouwmeester, Jian Wei Pan, Klaus Mattle, Manfred Eibl, Harald Weinfurter & Anton Zeilinger

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1 Experimental quantum teleportation Dirk Bouwmeester, Jian Wei Pan, Klaus Mattle, Manfred Eibl, Harald Weinfurter & Anton Zeilinger NATURE VOL DECEMBER 1997

2 Overview Motivation General theory behind teleportation Experimental setup Applications of teleportation New research from this study

3 Relaying quantum information is difficult Sending directly can take a lot of time Coherence can be lost in the transfer We can t just measure a particle s state and then reconstruct, because Each state is a superposition of many states. Once we measure the particle, it will collapse into only one state, and all the other information is lost

4 For example, a photon can be polarized or in a superposition of polarized states. Beam Splitter: horizontally polarized photons are reflected, vertically polarized photons are transmitted The measurement projects the photon onto one polarization or the other, and we lose information about the original state

5 So, if we want to replicate the state, we can t just measure and reconstruct But we can use entanglement to replicate the state by quantum teleportation. We have Alice, with a particle in state <ψ 1. She wants to transfer it to Bob. Bob and Alice also have particles 2 and 3, which are entangled.

6 if Alice can entangle particle 1 and particle 2, then particle 3 should be in the same state as the original particle 1.

7 But how can we do this experimentally?

8 Experimental verification of teleportation theory 1993: Bennett et al. suggest it is possible to transfer the state of one particle to another using entanglement Spontaneous parametric downconversion provides a bright source of entangled photons Source: Wikimedia Commons Meanwhile: Quantum computing and cryptography develop 1995: Kwiat et al. build a bright entanglement source 1997: Bouwmeester et al. demonstrate experimental teleportation

9 Teleportation has been achieved, but Initial state is destroyed on Alice s side during teleportation (don t try this on yourself!) Bell state measurement has four outcomes, including the desired antisymmetric state Teleportation occurs just 25% of the time, 100% with extra classical information (slower) Desired state after measurement Other possible outcomes

10 But this kind of teleportation is good enough Complete basis of states can be teleported, allowing teleportation of general states Applications in quantum information: Quantum memory Data transfer through poor connections without losses Needs work, though: improved data rate? New science: Bell test on particles with no Common past

11 Citation Analysis Since its publication in 1997, it have been sited for 1991 times. Citation Ci Citation Citation by Year Citation By Journal

12 Recent Progress in Quantum Teleportation Experiments After the first Innsbruck experiment 2003 Experimental realization of freely propagating teleported qubits Jian Wei Pan et al., Nature 421 (2003) Experimental demonstration of five photon entanglement and open destination teleportation Zhi Zhao, et al. Nature 430, (1 July 2004) 2006 Experimental entanglement of six photons in graph states Chao Yang Lu, et al. Nature Physics 3, (2007)

13 Recent Progress in Quantum Teleportation Experiments (Continued) 2008 Memory built in quantum teleportation with photonic and atomic qubits Yu Ao Chen, et al, Nature Physics 4, (2008) Experimental set up for teleportation between photonic and atomic qubits.

14 Recent Progress in Quantum Teleportation Experiments (continued) 2010 Quantum teleportation achieved over 16 km University of Science and Technology of China, Tsinghua University (PhysOrg.com) Scientists in China have succeeded in teleporting information between photons further than ever before. They transported quantum information over a free space distance of 16 km (10 miles), much further than the few hundred meters previously achieved, which brings us closer to transmitting information over long distances without the need for a traditional signal.

15 Summary Observed teleportation of photon polarization states Teleportation can be used to realize a quantum computer Fueled new research involving more photons and information transfer between different particles