When taking leave or departing from any place, "be back" is a commonly used phrase. However, there are several synonyms to convey the same message. You can use the phrases "return shortly," "be right back," "back in a bit," "back in a jiffy," or "back in a sec." Similarly, "I'll be back soon," "I'll be back shortly," and "I will return shortly" can all be used interchangeably. These synonyms can help you add variety to your communication and can be used in a formal or casual setting. Choosing the right phrase that suits the context will help you convey your message more effectively.