Phys.org November 9, 2021 Researchers at the Lawrence Berkeley National Laboratory have demonstrated a new way to control qubits by substituting the larger, more costly traditional RF control systems with smaller interactive mixing modules. The modular system has high -reliability, delivering high-resolution, low-noise RF signals needed to manipulate and measure the superconducting qubit at room temperature. To do so, they shifted the qubit manipulation and measurement signal frequency between the electronics baseband and the quantum system. According to the researchers their system could be expanded to other quantum information science platforms, and RF mixing can be expanded to higher frequencies. […]
Tag Archives: Qubits
Making progress towards quantum technologies based on magnetic molecules
Nanowerk October 15, 2021 Electrical control of spins at the nanoscale offers significant architectural advantages in spintronics. However, the electric-field sensitivities reported so far are rather weak. An international team of researchers (UK, Spain) showed that one path is to identify an energy scale in the spin spectrum that is associated with a structural degree of freedom with a substantial electrical polarizability. They studied an example of a molecular nanomagnet in which a small structural distortion establishes clock transitions in the spin spectrum; the fact that this distortion is associated with an electric dipole allowed them to control the clock-transition energy […]
All-nitride superconducting qubit made on a silicon substrate
Science Daily September 20, 2021 Researchers in Japan have developed superconducting qubits based on NbN/AlN/NbN epitaxial Josephson junctions on silicon substrates which promise to overcome the drawbacks of qubits based on Al/AlOx/Al junctions. The all-nitride qubits have great advantages such as chemical stability against oxidation, resulting in fewer two-level fluctuators, feasibility for epitaxial tunnel barriers that reduce energy relaxation and dephasing, and a larger superconducting gap of ~5.2 meV for NbN, compared to ~0.3 meV for aluminum, which suppresses the excitation of quasiparticles. By replacing conventional MgO by a silicon substrate with a TiN buffer layer for epitaxial growth of […]
Quantum systems learn joint computing
EurekAlert February 24,2021 An international team of researchers (Germany, Spain) succeeded in connecting two qubit modules across a 60-meter distance in such a way that they effectively form a basic quantum computer with two qubits. They performed a quantum computing operation between two independent qubit setups in different laboratories. To generate entanglement between qubits for quantum computations they employed modules consisting of a single atom as a qubit that is positioned amidst two mirrors. Between these modules, they sent a photon, that is transported in the optical fiber. This photon is then entangled with the quantum states of the qubits […]
Blueprint for fault-tolerant qubits
EurekAlert February 18, 2021 The application of active error correction in a quantum computer is very complex and comes with an extensive use of hardware. An international team of researchers (Germany, Switzerland, the Netherlands) has proposed a design for a circuit with passive error correction. The circuit is designed in such a way that it is already inherently protected against environmental noise while still controllable. The concept thus bypasses the need for active stabilization in a highly hardware-efficient manner and would therefore be a promising candidate for a future large-scale quantum processor that has many qubits. By implementing a gyrator […]
Fifty perfect photons for ‘quantum supremacy’
Phys.org June 23, 2020 About 50 quantum building blocks are needed to solve problems whether they are in the form of photons or qubits. Photons can operate at room temperatures and they are more stable. But they must be perfect to get to the critical number of 50. An international team of researchers (the Netherlands, Germany) found that by playing with the crystal structure of the light source and dividing them into domains, it was possible to produce light with the desired properties. Varying the domains, however, is required for better tailoring of the light properties…read more. TECHNICAL ARTICLE
Light from stretchable sheets of atoms for quantum technologies
EurekAlert April 16, 2020 Unlike other nanomaterials used as quantum light sources, such as diamond, silicon carbide or gallium nitride hexagonal boron nitride is not brittle and comes with the unique stretchable mechanical properties of a van der Waals crystal. However, their spectral inhomogeneity currently limits their potential applications. Researchers in Australia applied tensile strain to quantum emitters embedded in few‐layer hBN films. They observed both red and blue spectral shifts with tuning magnitudes up to 65 meV. Rotation of the optical dipole in response to strain suggested the presence of a second excited state. They developed a theoretical model […]
Scientists Find Yet Another Way to Get Qubits Working at Room Temperature
Science Alert March 22, 2020 Defect-based quantum systems are often complicated by charge-state instabilities and interference by phonons, which can diminish spin-initialization fidelities and limit room-temperature operation. An international team of researchers (Hungary, Sweden, USA – Argonne National Laboratory, University of Chicago, IBM, Russia) has identified a pathway around these drawbacks by showing that an engineered quantum well can stabilize the charge state of a qubit. Using density-functional theory and experimental synchrotron X-ray diffraction studies they constructed a model for previously unattributed point defect centers in silicon carbide as a near-stacking fault axial divacancy and showed how this model explains […]
In leap for quantum computing, silicon quantum bits establish a long-distance relationship
EurekAlert December 25, 2019 Silicon spin qubits have several advantages over superconducting qubits – they retain their quantum state longer than competing qubit technologies and they could be manufactured at low cost. A team of researchers in the US (Princeton University, industry) connected the qubits via a “wire” which is a narrow cavity containing a photon that picks up the message from one qubit and transmits it to the next qubit. The two qubits were located about half a centimeter apart. The team succeeded in tuning both qubits independently of each other while still coupling them to the photon. An […]
Tuning into quantum: Scientists unlock signal frequency control of precision atom qubits
Phys.org July 13, 2018 In their experiments, an international team of researchers (Australia, USA – Purdue University) has confirmed the ability to tune neighbouring qubits into resonance without impacting each other. Creating engineered phosphorus molecules with different separations between the atoms within the molecule allows for families of qubits with different control frequencies. Each molecule can be operated individually by selecting the frequency that controls its electron spin. It creates a built-in address which will provide significant benefits for building a silicon quantum computer. By engineering the atomic placement of the atoms within the qubits in the silicon chip, the […]