Absolute Zero temperature is not achievable although a temperature close to it can be attained with the use of cry coolers, dilutions refrigerators and nuclear adiabatic demagnetisation. Laser cooling has resulted in attainment of a temperature than a billionth Kelvin.
The reason that absolute zero is is an impossible goal is that the work needed to remove heat from the gas increases. Once the temperature drops and in that way , an infinite amount of work would be needed to cool something to absolute zero.
In quantum term,this can be attributed to Heisenberg 's principle signifying more precisely regarding the speed of the particle, position and vice versa.
Hence the atoms inside the experiment, there must be uncertaintity in their momentum keeping them above absolute zero, unless the experiment is considered taking the whole universe.