Phys.org May 20, 2020 Building on the their 2017 demonstration of quantum control of a molecule, a team of researchers in the US (NIST, University of Colorado) successfully entangled two energy levels of a calcium atomic ion with two different pairs of rotational states of a calcium hydride molecular ion, which is a calcium ion bonded to a hydrogen atom. The molecular qubit had a transition frequency—the speed of cycling between two rotational states—of either low energy at 13.4 kilohertz (kHz, thousands of cycles per second) or high energy at 855 billion cycles per second (gigahertz or GHz). Molecules could […]
Tag Archives: Quantum entanglement
Quantum-entangled light from a vibrating membrane
Phys.org March 31, 2020 Optical quantum states propagate with ultralow attenuation and resilient to ubiquitous thermal noise. Mechanical systems are envisioned as versatile interfaces between photons and a variety of solid-state quantm information processing platforms. Researchers in Denmark generated entanglement between two propagating optical modes by coupling them to the same cryogenic mechanical system. The entanglement persisted at room temperature. They verified the inseparability of the bipartite state and fully characterized its logarithmic negativity by homodyne tomography. Combined with quantum interfaces between mechanical systems and solid-state qubit processors, this paves the way for mechanical systems enabling long-distance quantum information networking […]
Entangling photons generated millions of miles apart
Phys.org August 28, 2019 An international team of researchers (China, USA – Louisiana State University, Texas A&M University, Baylor University, Princeton University, Germany, UK) conducted an experiment to test quantum interference, entanglement, and nonlocality using two dissimilar photon sources, the Sun and a semiconductor quantum dot on the Earth, which are separated by approximately 150 million km. By making the photons indistinguishable in all degrees of freedom, they observed time-resolved two-photon quantum interference with a raw visibility of 0.796, well above the 0.5 classical limit, providing unambiguous evidence of the quantum nature of thermal light. Using the photons with no […]
Researchers create a ‘universal entangler’ for new quantum tech
Phys.org February 27, 2019 Using an entangling mechanism called an exponential-SWAP gate researchers at Yale University demonstrated the new technology by deterministically entangling encoded states in any chosen configuration or codes, each housed in two otherwise isolated, 3-D superconducting microwave cavities. The results provide a valuable building block for universal quantum computation using bosonic modes…read more. TECHNICAL ARTICLE
Entangling photons of different colors
Science Daily February 25, 2019 A team of researchers in the US (NIST, University of Maryland) created quantum-correlated pairs made up of one visible and one near-infrared photon. The visible-light partners can interact with trapped atoms, ions, or other systems that serve as quantum versions of computer memory while the near-infrared members of each couple are free to propagate over long distances through the optical fiber. The design methods can be easily applied to create many other visible-light/near-infrared pairs tailored to match specific systems of interest. In the future, by combining two of the entangled pairs with two quantum memories, […]
New study could hold key to hack-proof systems
Phys.org July 17, 2018 An international team of researchers (Austria, France, Czech Republic, Slovakia, Switzerland, Spain, UK) show how carefully constructed measurements in two bases (one of which is not orthonormal) can be used to faithfully and efficiently certify bipartite high-dimensional states and their entanglement for any physical platform. In an experimental set-up, they were able to verify 9-dimensional entanglement for a pair of photons on a 11-dimensional subspace each. The group is currently looking into a more direct use of this technique in actual quantum cryptography protocols and expect their technique to be widely applied in other quantum systems […]
How can you tell if a quantum memory is really quantum?
Phys.org May 23, 2018 Often it is difficult to tell whether a memory is storing quantum or merely classical information. The new test developed by an international team of researchers (Taiwan, Switzerland, Japan, Canada) uses a semiquantum framework that is very similar to that used in some tests of entanglement. By comparing the relative frequencies of the sent and received signals it is possible to estimate the time-like entanglement and therefore certify that a quantum memory can store quantum information. They showed that the new test is robust against noise and losses, and they expect that it should be possible […]