European XFEL produces record 300-attosecond hard X-ray flashes

A team at European XFEL focused hard X-ray pulses into a 180×330 nm spot, reaching peak intensity above 10²⁰ W/cm² with a duration of about 300 attoseconds. The April 2026 experiment at the MID instrument confirmed the result via amplified spontaneous emission in copper foil.

• Pulses lasted about 300 attoseconds, focused to a 180×330 nm spot
• Peak intensity exceeded 10²⁰ W/cm², a record for hard X-ray attosecond pulses
• ASE signal in copper foil independently confirmed the intensity calculation
• European XFEL expects its own AKB system in early 2027