Mantrap

Man-traps are physical security devices or constructions that can be designed to entrap a person on purpose
A man-trap in modern physical security protocols refers to a small space having two sets of interlocking doors such that the first set of doors must close before the second set opens. Identification may be required for each door, and possibly different measures for each door. For example, a key may open the first door, but a personal identification number entered on a number pad opens the second. Other methods of opening doors include proximity cards or biometric devices such as fingerprint readers or iris recognition scans.
Metal detectors are often built-in in order to prevent entrance of people carrying weapons. Such use is particularly frequent in banks and jewelry shops. "Man-traps" may be configured so that when an alarm is activated, all doors lock and trap the suspect between the doors in the "dead-space" or lock just one door to deny access to a secure space such as a data center or research lab.
In a lower-security variation of a man-trap, banks often locate automated teller machines within the dead-space between the entrance doors and the interior lobby doors to prevent ATM robbery and night-time walk-up robberies. Entry access by ATM card to the dead-space offers additional customer protection. They are also known as an air-lock in the security industry

Portions Taken From Wikipedia