Experimental quantumteleportation
Dirk Bouwmeester, Jian‐Wei Pan, Klaus Mattle, Manfred Eibl, Harald
Weinfurter & Anton Zeilinger
NATURE | VOL 390 | 11 DECEMBER 1997
Overview
• Motivation
• General theory behind teleportation
• Experimental setup
• Applications of teleportation
• New research from this study
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
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
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 <ψ1|. She wants to transfer it to Bob.
Bob and Alice also have particles 2 and 3, which are entangled.
…if Alice can entangle particle 1 and particle 2,
…then particle 3 should be in the same state as the original particle 1.
But how can we do this experimentally?
Experimental verification of teleportation theory
‐1993: Bennett et al. suggest it is possible to transfer the state of one particle to another using entanglement
Meanwhile: Quantum computing andcryptography develop
‐1995: Kwiat et al. build a bright entanglement source‐1997: Bouwmeester et al.demonstrate experimental teleportationSpontaneous parametric downconversion
provides a bright source of entangled photonsSource: Wikimedia Commons
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
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
Citation Analysis
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Recent Progress in Quantum Teleportation Experiments
After the first Innsbruck experiment• 2003‐Experimental realization offreely propagating teleported qubitsJian‐Wei Pan et al., Nature 421 (2003) 721‐725
• 2004‐Experimental demonstration of five‐photon entanglement and open‐destination teleportationZhi Zhao, et al. Nature 430, 54‐58 (1 July 2004)
• 2006‐Experimental entanglementof six photons in graph statesChao‐Yang Lu, et al. Nature Physics 3, 91 ‐ 95 (2007)
Recent Progress in Quantum Teleportation Experiments (Continued)• 2008‐Memory‐built‐in quantum teleportation with
photonic and atomic qubitsYu‐Ao Chen, et al, Nature Physics 4, 103 ‐ 107 (2008)
Experimental set‐up for teleportation between photonic and atomic qubits.
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 havesucceeded in teleporting information betweenphotons further than ever before. Theytransported quantum information over a freespace distance of 16 km (10 miles), muchfurther than the few hundred meterspreviously achieved, which brings us closer totransmitting information over long distanceswithout the need for a traditional signal.
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