A team of researchers has developed an optical lattice clock with a total systematic uncertainty of 8.1 × 10⁻¹⁹ in fractional frequency units, the lowest uncertainty of any clock to date. The clock uses a dilute ensemble of fermionic strontium atoms trapped in a vertically-oriented, shallow, one-dimensional optical lattice. The clock transition is the ultra-narrow ¹S₀ → ³P₀ transition, and the system is designed to minimize systematic effects such as black body radiation shifts, lattice light shifts, and Zeeman shifts. The team evaluated various systematic effects, including the black body radiation shift, which was corrected by measuring the 5s4d³D₁ lifetime with high precision. They also measured the second-order Zeeman coefficient on the least magnetically sensitive clock transition. All other systematic effects were found to have uncertainties below 1 × 10⁻¹⁹. The clock's high accuracy is achieved through precise control of environmental factors, including temperature, lattice depth, and magnetic fields. The system includes a magic lattice depth that cancels on-site interactions, reducing density shifts. The clock's performance is supported by a detailed evaluation of various systematic effects, including the black body radiation shift, which was corrected using a measured 5s4d³D₁ lifetime. The team also evaluated the lattice light shift and found it to be 3.2 × 10⁻¹⁹. The Zeeman shift was minimized by using the least magnetically sensitive clock transition. The team also evaluated the tunneling shift, which was found to be 2 × 10⁻²¹. The density shift was reduced by operating at a "magic lattice depth" where on-site and off-site interactions cancel each other. The team also evaluated other systematic shifts, including the background gas shift, which was found to be -4.7 × 10⁻¹⁹. The clock's performance is supported by a detailed evaluation of various systematic effects, including the black body radiation shift, which was corrected using a measured 5s4d³D₁ lifetime. The team also evaluated the lattice light shift and found it to be 3.2 × 10⁻¹⁹. The Zeeman shift was minimized by using the least magnetically sensitive clock transition. The team also evaluated the tunneling shift, which was found to be 2 × 10⁻²¹. The density shift was reduced by operating at a "magic lattice depth" where on-site and off-site interactions cancel each other. The team also evaluated other systematic shifts, including the background gas shift, which was found to be -4.7 × 10⁻¹⁹. The clock's performance is supported by a detailed evaluation of various systematic effects, including the black body radiation shift, which was corrected using a measured 5s4d³D₁ lifetime. The team also evaluated the lattice light shift andA team of researchers has developed an optical lattice clock with a total systematic uncertainty of 8.1 × 10⁻¹⁹ in fractional frequency units, the lowest uncertainty of any clock to date. The clock uses a dilute ensemble of fermionic strontium atoms trapped in a vertically-oriented, shallow, one-dimensional optical lattice. The clock transition is the ultra-narrow ¹S₀ → ³P₀ transition, and the system is designed to minimize systematic effects such as black body radiation shifts, lattice light shifts, and Zeeman shifts. The team evaluated various systematic effects, including the black body radiation shift, which was corrected by measuring the 5s4d³D₁ lifetime with high precision. They also measured the second-order Zeeman coefficient on the least magnetically sensitive clock transition. All other systematic effects were found to have uncertainties below 1 × 10⁻¹⁹. The clock's high accuracy is achieved through precise control of environmental factors, including temperature, lattice depth, and magnetic fields. The system includes a magic lattice depth that cancels on-site interactions, reducing density shifts. The clock's performance is supported by a detailed evaluation of various systematic effects, including the black body radiation shift, which was corrected using a measured 5s4d³D₁ lifetime. The team also evaluated the lattice light shift and found it to be 3.2 × 10⁻¹⁹. The Zeeman shift was minimized by using the least magnetically sensitive clock transition. The team also evaluated the tunneling shift, which was found to be 2 × 10⁻²¹. The density shift was reduced by operating at a "magic lattice depth" where on-site and off-site interactions cancel each other. The team also evaluated other systematic shifts, including the background gas shift, which was found to be -4.7 × 10⁻¹⁹. The clock's performance is supported by a detailed evaluation of various systematic effects, including the black body radiation shift, which was corrected using a measured 5s4d³D₁ lifetime. The team also evaluated the lattice light shift and found it to be 3.2 × 10⁻¹⁹. The Zeeman shift was minimized by using the least magnetically sensitive clock transition. The team also evaluated the tunneling shift, which was found to be 2 × 10⁻²¹. The density shift was reduced by operating at a "magic lattice depth" where on-site and off-site interactions cancel each other. The team also evaluated other systematic shifts, including the background gas shift, which was found to be -4.7 × 10⁻¹⁹. The clock's performance is supported by a detailed evaluation of various systematic effects, including the black body radiation shift, which was corrected using a measured 5s4d³D₁ lifetime. The team also evaluated the lattice light shift and