Phys.org December 10, 2024 Qubit connectivity on a planar surface is typically restricted to only a few neighboring qubits. Overcoming the complex multilayer packaging, external cabling, and fidelity limitations, a team of researchers in the US (University of Chicago, Argonne National Laboratory) proposed and developed a high-speed on-chip quantum processor that supported reconfigurable all-to-all coupling with a large on-off ratio. They implemented the design in a four-node quantum processor, built with a modular design comprising a wiring substrate coupled to two separate qubit-bearing substrates, each including two single-qubit nodes. Using the device they demonstrated reconfigurable controlled- gates across all qubit […]
Tag Archives: Qubits
Researchers demonstrate universal control of a quantum dot-based system with four singlet-triplet qubits
Phys.org November 13, 2024 The coherent control of interacting spins in semiconductor quantum dots is of interest for quantum information processing and studying quantum magnetism from the bottom up. Researchers in the Netherlands demonstrated a 2 × 4 germanium quantum dot array with full and controllable interactions between nearest-neighbour spins. As a demonstration of the level of control, they defined four singlet–triplet qubits in this system and showed two-axis single-qubit control of each qubit and SWAP-style two-qubit gates between all neighbouring qubit pairs, yielding average single-qubit gate and Bell state fidelities. Combining these operations, they implemented a circuit designed to generate and […]
Higher-order topological simulation unlocks new potential in quantum computers
Phys. org August 30, 2024 At present the range of viable applications with noisy intermediate-scale quantum (NISQ) devices remains limited by gate errors and the number of high-quality qubits. An international team of researchers (USA – Caltech, MIT, Singapore) developed an approach that places digital NISQ hardware as a versatile platform for simulating multi-dimensional condensed matter systems. Their method encoded a high-dimensional lattice in terms of many-body interactions on a reduced-dimension model, thereby taking full advantage of the exponentially large Hilbert space of the host quantum system. With circuit optimization and error mitigation techniques, they measured the topological state dynamics […]
Understanding quantum states: New research shows importance of precise topography in solid neon qubits
Phys.org June 26, 2024 Single electrons trapped on solid-neon surfaces, which have long coherence times, are promising platform for charge qubits. The actual quantum states of the trapped electrons have not been understood. A team of researchers in the USA (National High Magnetic Field Laboratory (Florida), Florida State University, University of Florida, FAMU-FSU College of Engineering) examined the electron’s interactions with neon surface topography and by evaluating the surface charges induced by the electron, they demonstrated its strong perpendicular binding to the neon surface. They revealed that surface bumps could bind an electron, forming unique quantum ring states that aligned […]
Modular, scalable hardware architecture for a quantum computer
MIT News May 29, 2024 Colour centres in diamond have emerged as a leading solid-state platform for advancing quantum technologies and recently achieved quantum advantage in secret key distribution. Blueprint studies indicate that general-purpose quantum computing using local quantum communication networks will require millions of physical qubits to encode thousands of logical qubits, presenting an open scalability challenge. An international team of researchers (MIT, DEVCOM, Army Research Laboratory, The MITRE Corporation, Cornell University, the Netherlands, Germany) introduced a modular quantum system-on-chip (QSoC) architecture that integrated thousands of individually addressable tin-vacancy spin qubits in two-dimensional arrays of quantum microchiplets into an […]
The ‘breath’ between atoms — a new building block for quantum technology
Science Daily June 1, 2023 Quantum light sources in which coupling between single photons and phonons can be controlled and harnessed enables quantum information transduction. Researchers at the University of Washington created quantum emitters featuring highly tunable coupling between excitons and phonons. The quantum emitters were formed in strain-induced quantum dots created in homobilayer WSe2. The colocalization of quantum-confined interlayer excitons and terahertz interlayer breathing-mode phonons, which directly modulated the exciton energy, led to a uniquely strong phonon coupling to single-photon emission. Due to the vertical dipole moment of the interlayer exciton, the phonon–photon interaction was electrically tunable to be […]
Proposed perovskite-based device combines aspects of electronics and photonics
Phys.org May 12, 2023 Hybrid perovskites have emerged as a promising material candidate for exciton-polariton (polariton) optoelectronics. Many applications demand precise control of polariton interactions. Thus far, the primary mechanisms by which polaritons relax in perovskites remain unclear. An international team of researchers (USA – MIT, Spain, Italy) sandwiched perovskite in between two precisely spaced reflective surfaces and stimulated them with laser beams. Then they were able to directly control the momentum of exciton-polariton pairs. The combined sate could be perturbed either with light or charge in a more energy-efficient manner. Halide perovskites harvest light well, and turn photons into […]
On-demand storage of photonic qubits at telecom wavelengths
Phys.org December 6, 2022 Researchers in China processed a fiber-integrated quantum memory at telecom wavelengths based on a laser-written waveguide fabricated in an erbium-doped yttrium silicate. Both ends of the waveguide memory were directly connected with fiber arrays with a fiber-to-fiber efficiency of 51%. Storage fidelity of 98.3(1)% was obtained for time-bin qubits encoded with single-photon-level coherent pulses, which is far beyond the maximal fidelity that can be achieved with a classical measure and prepared strategy. This device featured high reliability and easy scalability, and it can be directly integrated into fiber networks, which could play an essential role in […]
Unimon – A new qubit to boost quantum computers for useful applications
Nanowerk November 15, 2022 Superconducting qubits seem promising for useful quantum computers, but the currently wide-spread qubit designs and techniques do not yet provide high enough performance. Researchers in Finland have developed a superconducting-qubit type, the unimon, which combines the desired properties of increased anharmonicity, full insensitivity to dc charge noise, reduced sensitivity to flux noise, and a simple structure consisting only of a single Josephson junction in a resonator. In agreement with their quantum models, they measured the qubit frequency and increased anharmonicity at the optimal operation point. It yielded, 99.9% and 99.8% fidelity for 13 ns single-qubit gates on […]
What quantum information and snowflakes have in common, and what we can do about it
Science Daily June 15, 2022 Transducing quantum signals between disparate regimes of the electro-magnetic spectrum remains an outstanding goal. Many remote entanglement protocols require multiple qubit gates both preceding and following the upconversion of the quantum state, and thus an ideal transducer should impart minimal backaction on the qubit. A team of researchers in the US (University of Colorado, NIST) demonstrated readout of a superconducting transmon qubit through a low-backaction electro-optomechanical transducer. The modular nature of the transducer and circuit quantum electrodynamics system used in this work enabled complete isolation of the qubit from optical photons, and the backaction on […]