Question

How do measurements collapse quantum wavefunctions?​

Answer 1

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In quantum mechanics, wave function collapse occurs when a wave function—initially in a superposition of several eigenstates—reduces to a single eigenstate due to interaction with the external world. ... Historically Werner Heisenberg was the first to use the idea of wave function reduction to explain quantum measurement.

Answer 2

• ɪɴ ϙᴜᴀɴᴛᴜᴍ ᴍᴇᴄʜᴀɴɪᴄs, ᴡᴀᴠᴇ ғᴜɴᴄᴛɪᴏɴ ᴄᴏʟʟᴀᴘsᴇ ᴏᴄᴄᴜʀs ᴡʜᴇɴ ᴀ ᴡᴀᴠᴇ ғᴜɴᴄᴛɪᴏɴ—ɪɴɪᴛɪᴀʟʟʏ ɪɴ ᴀ sᴜᴘᴇʀᴘᴏsɪᴛɪᴏɴ ᴏғ sᴇᴠᴇʀᴀʟ ᴇɪɢᴇɴsᴛᴀᴛᴇs—ʀᴇᴅᴜᴄᴇs ᴛᴏ ᴀ sɪɴɢʟᴇ ᴇɪɢᴇɴsᴛᴀᴛᴇ ᴅᴜᴇ ᴛᴏ ɪɴᴛᴇʀᴀᴄᴛɪᴏɴ ᴡɪᴛʜ ᴛʜᴇ ᴇxᴛᴇʀɴᴀʟ ᴡᴏʀʟᴅ. ... ʜɪsᴛᴏʀɪᴄᴀʟʟʏ ᴡᴇʀɴᴇʀ ʜᴇɪsᴇɴʙᴇʀɢ ᴡᴀs ᴛʜᴇ ғɪʀsᴛ ᴛᴏ ᴜsᴇ ᴛʜᴇ ɪᴅᴇᴀ ᴏғ ᴡᴀᴠᴇ ғᴜɴᴄᴛɪᴏɴ ʀᴇᴅᴜᴄᴛɪᴏɴ ᴛᴏ ᴇxᴘʟᴀɪɴ ϙᴜᴀɴᴛᴜᴍ ᴍᴇᴀsᴜʀᴇᴍᴇɴᴛ.