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Xing-Can Yao,
Tian-Xiong Wang,
Hao-Ze Chen,
Wei-Bo Gao,
Austin G Fowler,
Robert Raussendorf,
Zeng-Bing Chen,
Nai-Le Liu,
Chao-Yang Lu,
You-Jin Deng,
Yu-Ao Chen,
Jian-Wei Pan
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ABSTRACT: Scalable quantum computing can be achieved only if quantum bits are manipulated in a fault-tolerant fashion. Topological error correction--a method that combines topological quantum computation with quantum error correction--has the highest known tolerable error rate for a local architecture. The technique makes use of cluster states with topological properties and requires only nearest-neighbour interactions. Here we report the experimental demonstration of topological error correction with an eight-photon cluster state. We show that a correlation can be protected against a single error on any quantum bit. Also, when all quantum bits are simultaneously subjected to errors with equal probability, the effective error rate can be significantly reduced. Our work demonstrates the viability of topological error correction for fault-tolerant quantum information processing.
Nature 02/2012; 482(7386):489-94. · 36.28 Impact Factor
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ABSTRACT: Using ultra-bright sources of pure-state entangled photons from parametric
down conversion, an eight-photon interferometer and post-selection detection,
we demonstrate the ability to experimentally manipulate eight individual
photons and report the creation of an eight-photon Schr\"odinger cat state with
an observed fidelity of $0.708 \pm 0.016$.
05/2011;
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ABSTRACT: We experimentally demonstrate an advanced linear-optical programmable quantum processor that combines two elementary single-qubit programmable quantum gates. We show that this scheme enables direct experimental probing of quantum commutation relations for Pauli operators acting on polarization states of single photons. Depending on a state of two-qubit program register, we can probe either commutation or anticommutation relations. Very good agreement between theory and experiment is observed, indicating high-quality performance of the implemented quantum processor.
Physical Review Letters 09/2010; 105(12):120402. · 7.37 Impact Factor
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ABSTRACT: The paradigm of measurement-based quantum computation opens new experimental
avenues to realize a quantum computer and deepens our understanding of quantum
physics. Measurement-based quantum computation starts from a highly entangled
universal resource state. For years, clusters states have been the only known
universal resources. Surprisingly, a novel framework namely quantum computation
in correlation space has opened new routes to implement measurement-based
quantum computation based on quantum states possessing entanglement properties
different from cluster states. Here we report an experimental demonstration of
every building block of such a model. With a four-qubit and a six-qubit state
as distinct from cluster states, we have realized a universal set of
single-qubit rotations, two-qubit entangling gates and further Deutsch's
algorithm. Besides being of fundamental interest, our experiment proves
in-principle the feasibility of universal measurement-based quantum computation
without using cluster states, which represents a new approach towards the
realization of a quantum computer.
04/2010;
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ABSTRACT: Coherent manipulation of a large number of qubits and the generation of entangled states between them has been an important goal and benchmark in quantum information science, leading to various applications such as measurement-based quantum computing
Nature Physics 03/2010; 6(5):331-335. · 18.97 Impact Factor
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ABSTRACT: We propose and demonstrate scheme for direct experimental testing of quantum commutation relations for Pauli operators. The implemented device is an advanced quantum processor that involves two programmable quantum gates. Depending on a state of two-qubit program register, we can test either commutation or anti-commutation relations. Very good agreement between theory and experiment is observed, indicating high-quality performance of the implemented quantum processor and reliable verification of commutation relations for Pauli operators. Comment: 4 pages, 3 figures, 2 tables, REVTeX4
02/2010;
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ABSTRACT: We experimentally demonstrate an optical controlled-NOT (CNOT) gate with arbitrary single inputs based on a 4-photon 6-qubit cluster state entangled both in polarization and spatial modes. We first generate the 6-qubit state, and then, by performing single-qubit measurements, the CNOT gate is applied to arbitrary single input qubits. To characterize the performance of the gate, we estimate its quantum process fidelity and prove its entangling capability. In addition, our results show that the gate cannot be reproduced by local operations and classical communication. Our experiment shows that such hyper-entangled cluster states are promising candidates for efficient optical quantum computation.
Physical Review Letters 01/2010; 104(2):020501. · 7.37 Impact Factor
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ABSTRACT: We report on the experimental realization of two different Bell inequality
tests based on six-qubit linear-type and Y-shape graph states. For each of
these states, the Bell inequalities tested are optimal in the sense that they
provide the maximum violation among all Bell inequalities with stabilizing
observables and possess the maximum resistance to noise.
06/2009;
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Wei-Bo Gao,
Austin G. Fowler,
Robert Raussendorf, Xing-Can Yao,
He Lu,
Ping Xu,
Chao-Yang Lu,
Cheng-Zhi Peng,
Youjin Deng,
Zeng-Bing Chen,
Jian-Wei Pan
[show abstract]
[hide abstract]
ABSTRACT: Topological error correction--a novel method to actively correct errors based
on cluster states with topological properties--has the highest order of
tolerable error rates known to date (10^{-2}). Moreover, the scheme requires
only nearest-neighbour interaction, particularly suitable for most physical
systems. Here we report the first experimental demonstration of topological
error correction with an 8-qubit optical cluster state. In the experiment, it
is shown that a correlation can be protected against a single error on any
single qubit. In addition, when all qubits are simultaneously subjected to
errors with equal probability, the effective error rate is significantly
reduced, clearly verifying the advantage of topological error correction. The
quantum gate with the error rate below the threshold is within the current
experimental technology. We believe topological error correction should be a
critical ingredient for the future large-scale quantum computation.
05/2009;
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ABSTRACT: Coherent manipulation of an increasing number of qubits for the generation of entangled states has been an important goal and benchmark in the emerging field of quantum information science. The multiparticle entangled states serve as physical resources for measurement-based quantum computing and high-precision quantum metrology. However, their experimental preparation has proved extremely challenging. To date, entangled states up to six, eight atoms, or six photonic qubits have been demonstrated. Here, by exploiting both the photons' polarization and momentum degrees of freedom, we report the creation of hyper-entangled six-, eight-, and ten-qubit Schr\"odinger cat states. We characterize the cat states by evaluating their fidelities and detecting the presence of genuine multi-partite entanglement. Small modifications of the experimental setup will allow the generation of various graph states up to ten qubits. Our method provides a shortcut to expand the effective Hilbert space, opening up interesting applications such as quantum-enhanced super-resolving phase measurement, graph-state generation for anyonic simulation and topological error correction, and novel tests of nonlocality with hyper-entanglement. Comment: 11 pages, 5 figures, comments welcome
09/2008;
