A team of researchers in Finland has set a new world record for how long a quantum bit, known as a qubit, can hold onto its information.<\/p>\n
They have pushed the coherence time of a superconducting transmon qubit to a full millisecond at best, with a median time of half a millisecond. That might sound brief, but in the world of quantum computing, it\u2019s a massive improvement that could change the game.<\/p>\n
Longer coherence times mean qubits can run more operations<\/a> and quantum computers can perform more calculations before errors start to appear.<\/p>\n \u201cA high-coherence qubit will benefit the research community and accelerate the global efforts on developing quantum sensors, quantum simulators, and quantum computers based on superconducting quantum technologies,\u201d the study authors note<\/a>.\u00a0<\/p>\n The way to a stable superconducting qubit<\/p>\n Qubits are extremely delicate. They easily lose their quantum state through interaction with their environment, a problem called decoherence. For years, scientists around the world have been trying to make qubits that can stay stable long enough to run complicated calculations.<\/p>\n Previously, the best echo coherence times reported for transmon qubits, a popular type used in many labs, hovered around 0.6 milliseconds<\/a> at most. Going beyond that has proven extremely difficult because even tiny bits of noise in the materials or measurement setup can cause the quantum state to collapse.<\/p>\n To overcome this, researchers at Aalto University in Finland designed and built a new type of transmon qubit with unusually high<\/a> coherence. They used ultra-clean superconducting films and fabricated a chip in a highly controlled cleanroom environment.<\/p>\n They carefully etched the circuits using electron-beam lithography (a technique used to draw tiny patterns on a chip) and precisely crafted the critical Josephson junctions, which act like the qubit\u2019s brain.\u00a0<\/p>\n The researchers also paid special attention to oxidation and material purity to reduce the kinds of microscopic flaws that qubits usually cause to fail early. Once the chip was built, it was cooled to near absolute zero using a dilution refrigerator.\u00a0<\/p>\n This low temperature helps protect the fragile quantum state. To measure performance, they used a specialized amplifier that picks up weak quantum signals without adding extra noise. Among the four qubits on the chip<\/a>, one (called Q2) performed exceptionally well.\u00a0<\/p>\n It showed a maximum coherence time of just over one millisecond, with a median value across tests of about 0.5 milliseconds, much longer than most devices reported before. Even better, these results were repeated across multiple experiments, proving the method was reliable.<\/p>\n \u201cThis result represents a significant step in the development of high-coherence superconducting qubits by approaching the millisecond mark for the energy relaxation and dephasing times of a transmon qubit,\u201d the study authors added.<\/p>\n What\u2019s next for quantum<\/p>\n This is a big step toward making quantum computers more practical. Longer-lasting qubits can handle more operations before they lose information, which means fewer errors and less need for complicated error-correction techniques.<\/p>\n<\/p>\n